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How to draw one line only one time

I'm using GDI+ to visualize the schema of some user-specified building.
There are no complex objects in it - all of them can be represented by rectangles.
I do it, but have one issue: many rectangles are overlap, e.g. then rooms are adjacent.
So some lines drawed many times!
This looks bad (fat line) and decrease the application performance (extra work).
Is there a way to draw each line only once on a screen?
My code (simplified) looks like this:
private void Visualizator_Paint( object sender, PaintEventArgs e )
{
if ( m_building == null ) return;
var g = e.Graphics;
// Smooth graphics output and scale
g.SmoothingMode = SmoothingMode.HighQuality;
ScaleGraphics( g );
...
foreach( var room in m_rooms )
{
RectangleF extent = room.Extent;
g.DrawRectangle( brownPen, extent.X, extent.Y, extent.Width, extent.Height );
}
...
}
void ScaleGraphics( Graphics g )
{
// Set margins inside the control client area in pixels
var margin = new Margins( 16, 16, 16, 16 );
// Set the domain of (x,y) values
var range = m_building.Extents;
// Make it smaller by 5%
range.Inflate( 0.05f * range.Width, 0.05f * range.Height );
// Scale graphics
ScaleGraphics( g, Visualizator, range, margin );
}
void ScaleGraphics( Graphics g, Control control, RectangleF domain, Margins margin )
{
// Find the drawable area in pixels (control-margins)
int W = control.Width - margin.Left - margin.Right;
int H = control.Height - margin.Bottom - margin.Top;
// Ensure drawable area is at least 1 pixel wide
W = Math.Max( 1, W );
H = Math.Max( 1, H );
// Find the origin (0,0) in pixels
float OX = margin.Left - W * ( domain.Left / domain.Width );
float OY = margin.Top + H * ( 1 + domain.Top / domain.Height );
// Find the scale to fit the control
float SX = W / domain.Width;
float SY = H / domain.Height;
// Transform the Graphics scene
if ( m_panPoint.IsEmpty )
m_panPoint = new PointF( OX, OY );
g.TranslateTransform( m_panPoint.X, m_panPoint.Y, MatrixOrder.Append );
g.ScaleTransform( SX * m_scale, -SY * m_scale );
}
Screenshot of defect:

I was unable to reproduce the blurring/smearing effect described in the question. However, the basic request to be able to avoid over-drawing lines seems reasonably clear and not terribly complicated to address. So I offer this class which can do that work:
/// <summary>
/// Consolidates horizontal and vertical lines.
/// </summary>
class LineConsolidator : IEnumerable<LineConsolidator.Line>
{
/// <summary>
/// A pair of points defining a line
/// </summary>
public struct Line
{
public Point Start { get; private set; }
public Point End { get; private set; }
public Line(Point start, Point end)
: this()
{
Start = start;
End = end;
}
}
private struct Segment
{
public int Start { get; private set; }
public int End { get; private set; }
public Segment(int start, int end)
: this()
{
if (end < start)
{
throw new ArgumentException("start must be less than or equal to end");
}
Start = start;
End = end;
}
public Segment Union(Segment other)
{
if (End < other.Start || other.End < Start)
{
throw new ArgumentException("Only overlapping segments may be consolidated");
}
return new Segment(
Math.Min(Start, other.Start),
Math.Max(End, other.End));
}
public Segment? Intersect(Segment other)
{
int start = Math.Max(Start, other.Start),
end = Math.Min(End, other.End);
if (end < start)
{
return null;
}
return new Segment(start, end);
}
}
private Dictionary<int, List<Segment>> _horizontalLines = new Dictionary<int, List<Segment>>();
private Dictionary<int, List<Segment>> _verticalLines = new Dictionary<int, List<Segment>>();
/// <summary>
/// Add horizontal line
/// </summary>
/// <param name="y">The Y coordinate of the line to add</param>
/// <param name="start">The first X coordinate of the line to add (must not be larger than <paramref name="end"/></param>
/// <param name="end">The second X coordinate of the line to add (must not be smaller than <paramref name="start"/></param>
/// <remarks>
/// This method submits a new horizontal line to the collection. It is merged with any other
/// horizontal lines with exactly the same Y coordinate that it overlaps.
/// </remarks>
public void AddHorizontal(int y, int start, int end)
{
_AddLine(y, new Segment(start, end), _horizontalLines);
}
/// <summary>
/// Add vertical line
/// </summary>
/// <param name="y">The X coordinate of the line to add</param>
/// <param name="start">The first Y coordinate of the line to add (must not be larger than <paramref name="end"/></param>
/// <param name="end">The second Y coordinate of the line to add (must not be smaller than <paramref name="start"/></param>
/// <remarks>
/// This method submits a new vertical line to the collection. It is merged with any other
/// vertical lines with exactly the same X coordinate that it overlaps.
/// </remarks>
public void AddVertical(int x, int start, int end)
{
_AddLine(x, new Segment(start, end), _verticalLines);
}
/// <summary>
/// Add all four sides of a rectangle as individual lines
/// </summary>
/// <param name="rect">The rectangle containing the lines to add</param>
public void AddRectangle(Rectangle rect)
{
AddHorizontal(rect.Top, rect.Left, rect.Right);
AddHorizontal(rect.Bottom, rect.Left, rect.Right);
AddVertical(rect.Left, rect.Top, rect.Bottom);
AddVertical(rect.Right, rect.Top, rect.Bottom);
}
/// <summary>
/// Gets all of the horizontal lines in the collection
/// </summary>
public IEnumerable<Line> HorizontalLines
{
get
{
foreach (var kvp in _horizontalLines)
{
foreach (var segment in kvp.Value)
{
yield return new Line(new Point(segment.Start, kvp.Key), new Point(segment.End, kvp.Key));
}
}
}
}
/// <summary>
/// Gets all of the vertical lines in the collection
/// </summary>
public IEnumerable<Line> VerticalLines
{
get
{
foreach (var kvp in _verticalLines)
{
foreach (var segment in kvp.Value)
{
yield return new Line(new Point(kvp.Key, segment.Start), new Point(kvp.Key, segment.End));
}
}
}
}
private static void _AddLine(int lineKey, Segment newSegment, Dictionary<int, List<Segment>> segmentKeyToSegments)
{
// Get the list of segments for the given key (X for vertical lines, Y for horizontal lines)
List<Segment> segments;
if (!segmentKeyToSegments.TryGetValue(lineKey, out segments))
{
segments = new List<Segment>();
segmentKeyToSegments[lineKey] = segments;
}
int isegmentInsert = 0, isegmentMergeFirst = -1, ilineSegmentLast = -1;
// Find all existing segments that should be merged with the new one
while (isegmentInsert < segments.Count && segments[isegmentInsert].Start <= newSegment.End)
{
Segment? intersectedSegment = newSegment.Intersect(segments[isegmentInsert]);
if (intersectedSegment != null)
{
// If they overlap, merge them together, keeping track of all the existing
// segments which were merged
newSegment = newSegment.Union(segments[isegmentInsert]);
if (isegmentMergeFirst == -1)
{
isegmentMergeFirst = isegmentInsert;
}
ilineSegmentLast = isegmentInsert;
}
isegmentInsert++;
}
if (isegmentMergeFirst == -1)
{
// If there was no merge, just insert the new segment
segments.Insert(isegmentInsert, newSegment);
}
else
{
// If more than one segment was merged, remove all but one
if (ilineSegmentLast > isegmentMergeFirst)
{
segments.RemoveRange(isegmentMergeFirst + 1, ilineSegmentLast - isegmentMergeFirst);
}
// Copy the new, merged segment back to the first original segment's slot
segments[isegmentMergeFirst] = newSegment;
}
}
public IEnumerator<LineConsolidator.Line> GetEnumerator()
{
return HorizontalLines.Concat(VerticalLines).GetEnumerator();
}
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
}
Note that this is based on integer coordinates. It's a little trickier to apply this sort of logic to floating point coordinates, if one is actually concerned about accommodating round-off error. But if the floating point coordinates are assured of always coming from the same source when they overlap, then they will meet the equality condition this implementation requires and you can just change the types to floating point.
I included the properties to retrieve just the horizontal or vertical lines, so that I could draw them differently from each other (different line end-caps) to verify the algorithm was working. Normally I think you'd just enumerate the whole collection when drawing.
You use it by first creating an empty instance of the collection, then adding your rectangles (or individual lines if desired) via the AddRectangle() method, then finally enumerating all of the resulting lines.
I would expect this to perform just fine up to thousands of lines or so. In my tests, I just recreated the collection from scratch every time I painted the window.
It might perform well enough even at higher magnitudes depending on the PC, but I didn't try to do any specific optimizations, opting instead for easy-to-understand code. In a situation where you're dealing with an extremely large number of rectangles, you might want to keep a persistent instance to collect lines/rectangles as they are generated. Then you don't have to regenerate it every paint event. That may or may not then require adding features to the class to support removal of lines.

How to check Ray Picking Cylinders XNA

I'm drawing cylinders using the primitives provided by XNA, and what I want to do is, when the mouse hovers on a cylinder, I detect it. I tried using bounding spheres but it didn't work, as it wasn't accurate. I don't know what to do. Any help?
Summary of what I want to do.
1- Create bounding Box for this Cylinder
2- Rotate this bounding Box.
CODE TO DRAW CYLINDER can be found here
http://xbox.create.msdn.com/en-US/education/catalog/sample/primitives_3d
#region File Description
//-----------------------------------------------------------------------------
// CylinderPrimitive.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion
#region Using Statements
using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
#endregion
namespace TheProteinBundle
{
/// <summary>
/// Geometric primitive class for drawing cylinders.
/// </summary>
public class CylinderPrimitive : GeometricPrimitive
{
/// <summary>
/// Constructs a new cylinder primitive, using default settings.
/// </summary>
public CylinderPrimitive(GraphicsDevice graphicsDevice)
: this(graphicsDevice, 1, 1, 32)
{
}
/// <summary>
/// Constructs a new cylinder primitive,
/// with the specified size and tessellation level.
/// </summary>
public CylinderPrimitive(GraphicsDevice graphicsDevice,
float height, float diameter, int tessellation)
{
if (tessellation < 3)
throw new ArgumentOutOfRangeException("tessellation");
height /= 2;
float radius = diameter / 2;
// Create a ring of triangles around the outside of the cylinder.
for (int i = 0; i < tessellation; i++)
{
Vector3 normal = GetCircleVector(i, tessellation);
AddVertex(normal * radius + Vector3.Up * height, normal);
AddVertex(normal * radius + Vector3.Down * height, normal);
AddIndex(i * 2);
AddIndex(i * 2 + 1);
AddIndex((i * 2 + 2) % (tessellation * 2));
AddIndex(i * 2 + 1);
AddIndex((i * 2 + 3) % (tessellation * 2));
AddIndex((i * 2 + 2) % (tessellation * 2));
}
// Create flat triangle fan caps to seal the top and bottom.
CreateCap(tessellation, height, radius, Vector3.Up);
CreateCap(tessellation, height, radius, Vector3.Down);
InitializePrimitive(graphicsDevice);
base.boundingSphere.Center = Vector3.Zero;
if (height > diameter)
base.boundingSphere.Radius = height;
else
base.boundingSphere.Radius = diameter;
}
/// <summary>
/// Helper method creates a triangle fan to close the ends of the cylinder.
/// </summary>
void CreateCap(int tessellation, float height, float radius, Vector3 normal)
{
// Create cap indices.
for (int i = 0; i < tessellation - 2; i++)
{
if (normal.Y > 0)
{
AddIndex(CurrentVertex);
AddIndex(CurrentVertex + (i + 1) % tessellation);
AddIndex(CurrentVertex + (i + 2) % tessellation);
}
else
{
AddIndex(CurrentVertex);
AddIndex(CurrentVertex + (i + 2) % tessellation);
AddIndex(CurrentVertex + (i + 1) % tessellation);
}
}
// Create cap vertices.
for (int i = 0; i < tessellation; i++)
{
Vector3 position = GetCircleVector(i, tessellation) * radius +
normal * height;
AddVertex(position, normal);
}
}
/// <summary>
/// Helper method computes a point on a circle.
/// </summary>
static Vector3 GetCircleVector(int i, int tessellation)
{
float angle = i * MathHelper.TwoPi / tessellation;
float dx = (float)Math.Cos(angle);
float dz = (float)Math.Sin(angle);
return new Vector3(dx, 0, dz);
}
}
}
Using this class
#region File Description
//-----------------------------------------------------------------------------
// GeometricPrimitive.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion
#region Using Statements
using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
#endregion
namespace TheProteinBundle
{
/// <summary>
/// Base class for simple geometric primitive models. This provides a vertex
/// buffer, an index buffer, plus methods for drawing the model. Classes for
/// specific types of primitive (CubePrimitive, SpherePrimitive, etc.) are
/// derived from this common base, and use the AddVertex and AddIndex methods
/// to specify their geometry.
/// </summary>
public abstract class GeometricPrimitive : IDisposable
{
#region Fields
// During the process of constructing a primitive model, vertex
// and index data is stored on the CPU in these managed lists.
List<VertexPositionNormal> vertices = new List<VertexPositionNormal>();
List<ushort> indices = new List<ushort>();
// Once all the geometry has been specified, the InitializePrimitive
// method copies the vertex and index data into these buffers, which
// store it on the GPU ready for efficient rendering.
VertexBuffer vertexBuffer;
IndexBuffer indexBuffer;
BasicEffect basicEffect;
public BoundingSphere boundingsphere2;
public BoundingSphere boundingSphere;
public Matrix world;
#endregion
#region Initialization
/// <summary>
/// Adds a new vertex to the primitive model. This should only be called
/// during the initialization process, before InitializePrimitive.
/// </summary>
protected void AddVertex(Vector3 position, Vector3 normal)
{
vertices.Add(new VertexPositionNormal(position, normal));
}
/// <summary>
/// Adds a new index to the primitive model. This should only be called
/// during the initialization process, before InitializePrimitive.
/// </summary>
protected void AddIndex(int index)
{
if (index > ushort.MaxValue)
throw new ArgumentOutOfRangeException("index");
indices.Add((ushort)index);
}
/// <summary>
/// Queries the index of the current vertex. This starts at
/// zero, and increments every time AddVertex is called.
/// </summary>
protected int CurrentVertex
{
get { return vertices.Count; }
}
/// <summary>
/// Once all the geometry has been specified by calling AddVertex and AddIndex,
/// this method copies the vertex and index data into GPU format buffers, ready
/// for efficient rendering.
protected void InitializePrimitive(GraphicsDevice graphicsDevice)
{
// Create a vertex declaration, describing the format of our vertex data.
// Create a vertex buffer, and copy our vertex data into it.
vertexBuffer = new VertexBuffer(graphicsDevice,
typeof(VertexPositionNormal),
vertices.Count, BufferUsage.None);
vertexBuffer.SetData(vertices.ToArray());
// Create an index buffer, and copy our index data into it.
indexBuffer = new IndexBuffer(graphicsDevice, typeof(ushort),
indices.Count, BufferUsage.None);
indexBuffer.SetData(indices.ToArray());
// Create a BasicEffect, which will be used to render the primitive.
basicEffect = new BasicEffect(graphicsDevice);
basicEffect.EnableDefaultLighting();
}
/// <summary>
/// Finalizer.
/// </summary>
~GeometricPrimitive()
{
Dispose(false);
}
/// <summary>
/// Frees resources used by this object.
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Frees resources used by this object.
/// </summary>
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
if (vertexBuffer != null)
vertexBuffer.Dispose();
if (indexBuffer != null)
indexBuffer.Dispose();
if (basicEffect != null)
basicEffect.Dispose();
}
}
#endregion
public void TransformBoundingSphere(Matrix TransformToWorld)
{
boundingSphere.Transform(ref TransformToWorld, out boundingsphere2);
}
public bool CheckRayIntersection(Ray ray)
{
if (ray.Intersects(boundingsphere2).HasValue) return true;
return false;
}
#region Draw
/// <summary>
/// Draws the primitive model, using the specified effect. Unlike the other
/// Draw overload where you just specify the world/view/projection matrices
/// and color, this method does not set any renderstates, so you must make
/// sure all states are set to sensible values before you call it.
/// </summary>
public void Draw(Effect effect)
{
GraphicsDevice graphicsDevice = effect.GraphicsDevice;
// Set our vertex declaration, vertex buffer, and index buffer.
graphicsDevice.SetVertexBuffer(vertexBuffer);
graphicsDevice.Indices = indexBuffer;
foreach (EffectPass effectPass in effect.CurrentTechnique.Passes)
{
effectPass.Apply();
int primitiveCount = indices.Count / 3;
graphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0,
vertices.Count, 0, primitiveCount);
}
}
/// <summary>
/// Draws the primitive model, using a BasicEffect shader with default
/// lighting. Unlike the other Draw overload where you specify a custom
/// effect, this method sets important renderstates to sensible values
/// for 3D model rendering, so you do not need to set these states before
/// you call it.
/// </summary>
public void Draw(Matrix world, Matrix view, Matrix projection, Color color)
{
// Set BasicEffect parameters.
basicEffect.World = world;
basicEffect.View = view;
basicEffect.Projection = projection;
basicEffect.DiffuseColor = color.ToVector3();
basicEffect.Alpha = color.A / 255.0f;
GraphicsDevice device = basicEffect.GraphicsDevice;
device.DepthStencilState = DepthStencilState.Default;
if (color.A < 255)
{
// Set renderstates for alpha blended rendering.
device.BlendState = BlendState.AlphaBlend;
}
else
{
// Set renderstates for opaque rendering.
device.BlendState = BlendState.Opaque;
}
// Draw the model, using BasicEffect.
Draw(basicEffect);
}
#endregion
}
}

Multithreading Update with ReaderWriterLockSlim

I think I made a huge error when I first started designing my game and would give you some or even all of my code but it is just too complex. So please bear with me.
Now that I get to the more advanced stages of my design I am running into major trouble with threading.
During update I run 3 tasks simultaneously. Update, HitTesting and AI which are even split up into even more threads.
Updating needs to do the movement (including physics) and animation of all my objects.
HitTesting does all Hit testing between thousands of objects and still needs a lot of optimizing…. Things like Devide and conquer to get right.
AI issues commands to objects that are executed by the update cycle. Things like turn left or right, fire, etc.
And of course we have
draw… or in my case GetSprites during draw. That must have full priority over all but the update process.
And the yet unimplemented sound and message system.
As you can see this is not an optimal process for multitasking as they all function on the same objects but it needs to be.
So… I thought to implement System.Threading.ReaderWriterLockSlim
And here is my real question: How do I do that?
Since Update is the only writer to my draw data.
Drawing is a pure Reader
HitTesting might need to recalculate the boundingRectangle and Matrix but that does not influence Drawing
AI only needs to read position data and issue commands, read by Update on the next cycle and is separated in an group of separate classes (I call it master/puppet but probably has an official/better name)
Does it make sense to implement different ReaderWriterLockSlim objects to lock the different properties a thread could need?
I would like to have control during update to bypass a locked object (either by AI or HitTesting) and take the next one so that I can do it later when it is unlocked (or even skip it if update is taking too long but do it on the next cycle)
Does any of you know a book or site on advanced threading. Not the usual little examples I find everywhere so I can figure this out?
I have been stuck for more than a week now and I would like to proceed.
Any help appreciated.
This is the code I use for collision detection between objects. I converted it from a c++ example I found a long time ago but can't remember where.
public abstract class HitTestInfo : Object
{
static protected Random RND = new Random();
static protected Dictionary<String, Color[]> m_TextureDataDictionary;
public static Matrix GetMatrix(iSpriteInfo vDrawObject)
{
Matrix Transform =
Matrix.CreateTranslation(new Vector3(-vDrawObject.Origin, 0.0f)) *
Matrix.CreateScale(vDrawObject.Scale) *
Matrix.CreateRotationZ(vDrawObject.Angle) *
Matrix.CreateTranslation(new Vector3(vDrawObject.X, vDrawObject.Y, 0.0f));
return Transform;
}
/// <summary>
/// Calculates an axis aligned rectangle which fully contains an arbitrarily
/// transformed axis aligned rectangle.
/// </summary>
/// <param name="rectangle">Original bounding rectangle.</param>
/// <param name="transform">World transform of the rectangle.</param>
/// <returns>A new rectangle which contains the trasnformed rectangle.</returns>
public static Rectangle CalculateBoundingRectangle(Rectangle vrectangle,
Matrix transform)
{
Rectangle rectangle = vrectangle;
rectangle.X = 0;
rectangle.Y = 0;
// Get all four corners in local space
Vector2 leftTop = new Vector2(rectangle.Left, rectangle.Top);
Vector2 rightTop = new Vector2(rectangle.Right, rectangle.Top);
Vector2 leftBottom = new Vector2(rectangle.Left, rectangle.Bottom);
Vector2 rightBottom = new Vector2(rectangle.Right, rectangle.Bottom);
// Transform all four corners into work space
Vector2.Transform(ref leftTop, ref transform, out leftTop);
Vector2.Transform(ref rightTop, ref transform, out rightTop);
Vector2.Transform(ref leftBottom, ref transform, out leftBottom);
Vector2.Transform(ref rightBottom, ref transform, out rightBottom);
// Find the minimum and maximum extents of the rectangle in world space
Vector2 min = Vector2.Min(Vector2.Min(leftTop, rightTop),
Vector2.Min(leftBottom, rightBottom));
Vector2 max = Vector2.Max(Vector2.Max(leftTop, rightTop),
Vector2.Max(leftBottom, rightBottom));
// Return that as a rectangle
return new Rectangle((int)min.X, (int)min.Y,
(int)(max.X - min.X), (int)(max.Y - min.Y));
}
/// <summary>
/// Determines if there is overlap of the non-transparent pixels between two
/// sprites.
/// </summary>
/// <param name="transformA">World transform of the first sprite.</param>
/// <param name="widthA">Width of the first sprite's texture.</param>
/// <param name="heightA">Height of the first sprite's texture.</param>
/// <param name="dataA">Pixel color data of the first sprite.</param>
/// <param name="transformB">World transform of the second sprite.</param>
/// <param name="widthB">Width of the second sprite's texture.</param>
/// <param name="heightB">Height of the second sprite's texture.</param>
/// <param name="dataB">Pixel color data of the second sprite.</param>
/// <returns>True if non-transparent pixels overlap; false otherwise</returns>
public static bool IntersectPixels(
Matrix transformA, int widthA, int heightA, Color[] dataA,
Matrix transformB, int widthB, int heightB, Color[] dataB)
{
// Calculate a matrix which transforms from A's local space into
// world space and then into B's local space
Matrix transformAToB = transformA * Matrix.Invert(transformB);
// When a point moves in A's local space, it moves in B's local space with a
// fixed direction and distance proportional to the movement in A.
// This algorithm steps through A one pixel at a time along A's X and Y axes
// Calculate the analogous steps in B:
Vector2 stepX = Vector2.TransformNormal(Vector2.UnitX, transformAToB);
Vector2 stepY = Vector2.TransformNormal(Vector2.UnitY, transformAToB);
// Calculate the top left corner of A in B's local space
// This variable will be reused to keep track of the start of each row
Vector2 yPosInB = Vector2.Transform(Vector2.Zero, transformAToB);
// For each row of pixels in A
for (int yA = 0; yA < heightA; yA++)
{
// Start at the beginning of the row
Vector2 posInB = yPosInB;
// For each pixel in this row
for (int xA = 0; xA < widthA; xA++)
{
// Round to the nearest pixel
int xB = (int)Math.Round(posInB.X);
int yB = (int)Math.Round(posInB.Y);
// If the pixel lies within the bounds of B
if (0 <= xB && xB < widthB &&
0 <= yB && yB < heightB)
{
// Get the colors of the overlapping pixels
Color colorA = dataA[xA + yA * widthA];
Color colorB = dataB[xB + yB * widthB];
// If both pixels are not completely transparent,
if (colorA.A != 0 && colorB.A != 0)
{
// then an intersection has been found
return true;
}
}
// Move to the next pixel in the row
posInB += stepX;
}
// Move to the next row
yPosInB += stepY;
}
// No intersection found
return false;
}
public static List<CollisionData> CollisionCheck<T1, T2>(List<T1> List1, List<T2> List2)
{
List<CollisionData> RetList = new List<CollisionData>();
foreach (T1 obj1 in List1)
{
iSpriteInfo SI1 = obj1 as iSpriteInfo;
if (SI1 != null)
{
Matrix Matrix1 = SI1.Matrix;
Rectangle Rect1 = SI1.BoundingRectangle;
Color[] TextureData1 = SI1.TextureData;
foreach (T2 obj2 in List2)
{
iSpriteInfo SI2 = obj2 as iSpriteInfo;
if (SI1 != null)
{
Matrix Matrix2 = SI2.Matrix;
Rectangle Rect2 = SI2.BoundingRectangle;
Color[] TextureData2 = SI2.TextureData;
// The per-pixel check is expensive, so check the bounding rectangles
// first to prevent testing pixels when collisions are impossible.
if (Rect1.Intersects(Rect2))
{
// Check collision with Player and planets
if (IntersectPixels(Matrix1, (int)SI1.DestinationRectangle.Width,
(int)SI1.DestinationRectangle.Height, TextureData1,
Matrix2, (int)SI2.DestinationRectangle.Width,
(int)SI2.DestinationRectangle.Height, TextureData2))
{
RetList.Add(new CollisionData(SI1, SI2));
}
}
}
}
}
}
return RetList;
}
public static List<CollisionData> CollisionCheck<T1, T2>(T1 Obj1, List<T2> List2)
{
List<CollisionData> RetList = new List<CollisionData>();
lock (Obj1)
{
lock (List2)
{
iSpriteInfo SI1 = Obj1 as iSpriteInfo;
if (SI1 != null)
{
Matrix Matrix1 = SI1.Matrix;
Rectangle Rect1 = SI1.BoundingRectangle;
Color[] TextureData1 = SI1.TextureData;
foreach (T2 obj2 in List2)
{
iSpriteInfo SI2 = obj2 as iSpriteInfo;
if (SI1 != null)
{
Matrix Matrix2 = SI2.Matrix;
Rectangle Rect2 = SI2.BoundingRectangle;
Color[] TextureData2 = SI2.TextureData;
// The per-pixel check is expensive, so check the bounding rectangles
// first to prevent testing pixels when collisions are impossible.
if (Rect1.Intersects(Rect2))
{
// Check collision with Player and planets
if (IntersectPixels(Matrix1, (int)SI1.DestinationRectangle.Width,
(int)SI1.DestinationRectangle.Height, TextureData1,
Matrix2, (int)SI2.DestinationRectangle.Width,
(int)SI2.DestinationRectangle.Height, TextureData2))
{
RetList.Add(new CollisionData(SI1, SI2));
}
}
}
}
}
}
}
return RetList;
}
public static bool CollisionCheck<T1, T2>(T1 Obj1, T2 Obj2)
{
Matrix Matrix1;
Rectangle Rect1;
Color[] TextureData1;
Matrix Matrix2;
Rectangle Rect2;
Color[] TextureData2;
iSpriteInfo SI1 = Obj1 as iSpriteInfo;
if (SI1 != null)
{
lock (SI1)
{
Matrix1 = SI1.Matrix;
Rect1 = SI1.BoundingRectangle;
TextureData1 = SI1.TextureData;
}
iSpriteInfo SI2 = Obj2 as iSpriteInfo;
if (SI1 != null)
{
lock (SI2)
{
Matrix2 = SI2.Matrix;
Rect2 = SI2.BoundingRectangle;
TextureData2 = SI2.TextureData;
}
// The per-pixel check is expensive, so check the bounding rectangles
// first to prevent testing pixels when collisions are impossible.
if (Rect1.Intersects(Rect2))
{
// Check collision with Player and planets
if (IntersectPixels(Matrix1, (int)SI1.DestinationRectangle.Width,
(int)SI1.DestinationRectangle.Height, TextureData1,
Matrix2, (int)SI2.DestinationRectangle.Width,
(int)SI2.DestinationRectangle.Height, TextureData2))
{
return true;
}
}
}
}
return false;
}
}
iSpriteInfo is defined like this
public interface iSpriteInfo
{
float X { get; set; }
float Y { get; set; }
float Angle { get; set; }
Vector2 Origin { get; set; }
float Scale { get; set; }
float Depth { get; set; }
Color Color { get; set; }
Boolean Visible { get; set; }
Rectangle SourceRectangle { get; set; }
Rectangle DestinationRectangle { get; set; }
Rectangle BoundingRectangle { get; }
Matrix Matrix { get; }
SpriteSheet SpriteSheet { get; set; }
int SpriteSheetNum { get;}
Color[] TextureData { get; set; }
Vector2 GetVector2 { get; }
Vector3 GetVector3 { get; }
}

Some calculations in Update may be performed by GPU using CUDA technology (https://developer.nvidia.com/gpu-computing-sdk)

I can recommend several steps, and i hope some of them will be usefull:
1) Split your four spritesheets into several smaller spritesheets by category (Asteroids, Ships, bullets etc). MS always says, that several smaller image sources is better that one huge.
2) Get rid of background tiles for star field etc. Use HLSL to create starfield, explosions and effects. GPU perfomance is near "unlimited" for that kind of tasks and actually is good alternative of using CUDA.
3) Split collision detection process on independence tasks:
a) between active units
b) between active units and inactive environment(using collision map)
In strategies units should precalculate their path. So its nesessary to detect path intersections to recalculate pathes and prevent collisions.
All collisions should recalculates only in users viewport zone.
Active units should check collisions only near themselves.

How do I add Z-depth perspective to drawn lines in XNA?

I've been experimenting with drawing lines in XNA. I've got no trouble drawing lines in the X and Y directions, but whenever I try and add Z data to the points, there seems to be no effect.
Here's what I was hoping I could do by adding Z information (which I've simulated here by altering the Y and averaging the X points with the midpoint)
And here's what I'm actually getting (I've translated the 2nd line upwards to verify that there are, in fact, two lines getting drawn - when I only change the Z, the two lines get drawn on top of each other)
Am I messing up something basic with my perspective matrix? Skipping an important step? Code below is for the 2nd picture.
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
namespace WindowsGame3
{
/// <summary>
/// This is the main type for your game
/// </summary>
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
BasicEffect baseEffect;
VertexPositionColor[] vertices;
VertexPositionColor[] verticesTop;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
float AspectRatio = graphics.GraphicsDevice.Viewport.AspectRatio;
baseEffect = new BasicEffect(graphics.GraphicsDevice);
baseEffect.World = Matrix.Identity;
baseEffect.View = Matrix.Identity;
baseEffect.VertexColorEnabled = true;
baseEffect.Projection = Matrix.CreateOrthographicOffCenter
(0, graphics.GraphicsDevice.Viewport.Width, // left, right
graphics.GraphicsDevice.Viewport.Height, 0, // bottom, top
-100, 100); // near, far plane
vertices = new VertexPositionColor[7];
verticesTop = new VertexPositionColor[7];
vertices[0].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 1/8, graphics.GraphicsDevice.Viewport.Height * 5/7, 0);
vertices[0].Color = Color.Black;
vertices[1].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 2/8, graphics.GraphicsDevice.Viewport.Height * 5/7, 1/8);
vertices[1].Color = Color.Red;
vertices[2].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 3 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, -2/8);
vertices[2].Color = Color.Black;
vertices[3].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 4 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, 3/8);
vertices[3].Color = Color.Red;
vertices[4].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 5 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, -4/8);
vertices[4].Color = Color.Black;
vertices[5].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 6 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, 5/8);
vertices[5].Color = Color.Red;
vertices[6].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 7 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, -6/8);
vertices[6].Color = Color.Black;
for (int i = 0; i < 7; i++)
{
verticesTop[i] = vertices[i];
verticesTop[i].Position.Y -= 200; // remove this line once perspective is working
verticesTop[i].Position.Z += 100;
}
base.Initialize();
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
// TODO: use this.Content to load your game content here
}
/// <summary>
/// UnloadContent will be called once per game and is the place to unload
/// all content.
/// </summary>
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
/// <summary>
/// Allows the game to run logic such as updating the world,
/// checking for collisions, gathering input, and playing audio.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Update(GameTime gameTime)
{
// Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
// TODO: Add your update logic here
base.Update(gameTime);
}
/// <summary>
/// This is called when the game should draw itself.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
baseEffect.CurrentTechnique.Passes[0].Apply();
graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.LineStrip, vertices, 0, 6);
graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.LineStrip, verticesTop, 0, 6);
base.Draw(gameTime);
}
}
}

The function you are using Matrix.CreateOrthographicOffCenter() creates an orthogonal projection matrix which have no perspective.
Try using Matrix.CreatePerspectiveOffCenter() or Matrix.CreatePerspectiveFieldOfView() instead.
baseEffect.Projection = Matrix.CreatePerspectiveFieldOfView (
1.57f, // 90 degrees field of view
width / height, // aspect ratio
1.0f, // near plane, you want that as far as possible
10000.0f); // far plane, you want that as near as possible

Creating a 2D polygon in XNA

I have some sort of a problem. I'm new to XNA and want to draw a polygon shape that looks something like this (In the end, I want these point to be random):
So I read some articles and this is what I ended up with:
private VertexPositionColor[] vertices;
public TextureClass()
{
setupVertices();
}
public override void Render(SpriteBatch spriteBatch)
{
Texture2D texture = createTexture(spriteBatch);
spriteBatch.Draw(texture, new Rectangle((int)vertices[0].Position.X, (int)vertices[0].Position.Y, 30, 30), Color.Brown);
}
private Texture2D createTexture(SpriteBatch spriteBatch)
{
Texture2D texture = new Texture2D(spriteBatch.GraphicsDevice, 1, 1, false, SurfaceFormat.Color);
texture.SetData<Color>(new Color[] { Color.Brown });
return texture;
}
When I call Render it's starts drawing some squares as if it where in a loop. I'm just guessing I'm doing it all wrong. I would love it if someones points me into the right direction. Just creating a polygon and drawing it. It seemed so simple...

Here it what I have right now.
A class that generates a BasicEffect with some desired asignments.
public class StandardBasicEffect : BasicEffect
{
public StandardBasicEffect(GraphicsDevice graphicsDevice)
: base(graphicsDevice)
{
this.VertexColorEnabled = true;
this.Projection = Matrix.CreateOrthographicOffCenter(
0, graphicsDevice.Viewport.Width, graphicsDevice.Viewport.Height, 0, 0, 1);
}
public StandardBasicEffect(BasicEffect effect)
: base(effect) { }
public BasicEffect Clone()
{
return new StandardBasicEffect(this);
}
}
Here is my PolygonShape class
/// <summary>
/// A Polygon object that you will be able to draw.
/// Animations are being implemented as we speak.
/// </summary>
/// <param name="graphicsDevice">The graphicsdevice from a Game object</param>
/// <param name="vertices">The vertices in a clockwise order</param>
public PolygonShape(GraphicsDevice graphicsDevice, VertexPositionColor[] vertices)
{
this.graphicsDevice = graphicsDevice;
this.vertices = vertices;
this.triangulated = false;
triangulatedVertices = new VertexPositionColor[vertices.Length * 3];
indexes = new int[vertices.Length];
}
/// <summary>
/// Triangulate the set of VertexPositionColors so it will be drawn correcrly
/// </summary>
/// <returns>The triangulated vertices array</returns>}
public VertexPositionColor[] Triangulate()
{
calculateCenterPoint();{
setupIndexes();
for (int i = 0; i < indexes.Length; i++)
{
setupDrawableTriangle(indexes[i]);
}
triangulated = true;
return triangulatedVertices;
}
/// <summary>
/// Calculate the center point needed for triangulation.
/// The polygon will be irregular, so this isn't the actual center of the polygon
/// but it will do for now, as we only need an extra point to make the triangles with</summary>
private void calculateCenterPoint()
{
float xCount = 0, yCount = 0;
foreach (VertexPositionColor vertice in vertices)
{
xCount += vertice.Position.X;
yCount += vertice.Position.Y;
}
centerPoint = new Vector3(xCount / vertices.Length, yCount / vertices.Length, 0);
}
private void setupIndexes()
{
for (int i = 1; i < triangulatedVertices.Length; i = i + 3)
{
indexes[i / 3] = i - 1;
}
}
private void setupDrawableTriangle(int index)
{
triangulatedVertices[index] = vertices[index / 3]; //No DividedByZeroException?...
if (index / 3 != vertices.Length - 1)
triangulatedVertices[index + 1] = vertices[(index / 3) + 1];
else
triangulatedVertices[index + 1] = vertices[0];
triangulatedVertices[index + 2].Position = centerPoint;
}
/// <summary>
/// Draw the polygon. If you haven't called Triangulate yet, I wil do it for you.
/// </summary>
/// <param name="effect">The BasicEffect needed for drawing</param>
public void Draw(BasicEffect effect)
{
try
{
if (!triangulated)
Triangulate();
draw(effect);
}
catch (Exception exception)
{
throw exception;
}
}
private void draw(BasicEffect effect)
{
effect.CurrentTechnique.Passes[0].Apply();
graphicsDevice.DrawUserPrimitives<VertexPositionColor>(
PrimitiveType.TriangleList, triangulatedVertices, 0, vertices.Length);
}
Sorry, it's kind of alot. Now for my next quest. Animation my polygon.
Hope it helped fellow people with the same problem.

this code is useful to draw 2D lines, some calcs can be done into an initilization call, but i prefer for this example to keep all together.
public void DrawLine(VertexPositionColor[] Vertices)
{
Game.GraphicsDevice.DepthStencilState = DepthStencilState.Default;
Vector2 center;
center.X = Game.GraphicsDevice.Viewport.Width * 0.5f;
center.Y = Game.GraphicsDevice.Viewport.Height * 0.5f;
Matrix View = Matrix.CreateLookAt( new Vector3( center, 0 ), new Vector3( center, 1 ), new Vector3( 0, -1, 0 ) );
Matrix Projection = Matrix.CreateOrthographic( center.X * 2, center.Y * 2, -0.5f, 1 );
Effect EffectLines = Game.Content.Load<Effect>( "lines" );
EffectLines.CurrentTechnique = EffectLines.Techniques["Lines"];
EffectLines.Parameters["xViewProjection"].SetValue( View * Projection );
EffectLines.Parameters["xWorld"].SetValue( Matrix.Identity );
foreach ( EffectPass pass in EffectLines.CurrentTechnique.Passes )
{
pass.Apply( );
Game.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>
( PrimitiveType.LineList, Vertices, 0, Vertices.Length/2 );
}
}
LINES.FX
uniform float4x4 xWorld;
uniform float4x4 xViewProjection;
void VS_Basico(in float4 inPos : POSITION, in float4 inColor: COLOR0, out float4 outPos: POSITION, out float4 outColor:COLOR0 )
{
float4 tmp = mul (inPos, xWorld);
outPos = mul (tmp, xViewProjection);
outColor = inColor;
}
float4 PS_Basico(in float4 inColor:COLOR) :COLOR
{
return inColor;
}
technique Lines
{
pass Pass0
{
VertexShader = compile vs_2_0 VS_Basico();
PixelShader = compile ps_2_0 PS_Basico();
FILLMODE = SOLID;
CULLMODE = NONE;
}
}

I worked with XNA in the past on a physics simulation where I had to draw bounding boxes with GraphicsDevice.DrawIndexedPrimitives (You should google or MSDN for this function for more worked examples.)
The below code is what I used in my project for drawing a 3D geometry.
/// <summary>
/// Draw the primitive.
/// </summary>
/// <param name="world">World Matrix</param>
/// <param name="view">View Matrix</param>
/// <param name="projection">Projection Matrix</param>
/// <param name="color">Color of the primitive</param>
public void Draw(Matrix world, Matrix view, Matrix projection, Color color)
{
_mGraphicsDevice.VertexDeclaration = _mVertexDeclaration;
_mGraphicsDevice.Vertices[0].SetSource(_mVertexBuffer, 0, VertexPositionNormal.SizeInBytes);
_mGraphicsDevice.Indices = _mIndexBuffer;
_mBasicEffect.DiffuseColor = color.ToVector3();
_mBasicEffect.World = _mTransform * world;
_mBasicEffect.View = view;
_mBasicEffect.Projection = projection;
int primitiveCount = _mIndex.Count / 3;
_mBasicEffect.Begin();
foreach (EffectPass pass in _mBasicEffect.CurrentTechnique.Passes)
{
pass.Begin();
_mGraphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _mVertex.Count, 0, primitiveCount);
pass.End();
}
_mBasicEffect.End();
}
This function is a member method of a geometry object (class) and is called from the Game class' Draw(GameTime) method