Hi, not sure if this is the right place to post this but...
I recently had a reason to draw some 2D lines and points with XNA. After doing some inept googling etc, I didn't find anything that really fitted what I was after. So after doing some reading:
How To: Draw Points, Lines, and Other 3D Primitives I made a line batch and point batch set of classes. Here are the rotten fruits of my labours. They are pretty basic with plenty of room for improvement. I used a generic list rather than a fixed length vertex array for flexibility. It won't be the fastest but you can easily swap this out. As mentioned earlier they are 2D - they use Vertex2 and an orthographic off center projection matrix.
The PointBatch...
using System.Collections.Generic;
using Microsoft.Xna.Framework.Graphics;
using Vector2 = Microsoft.Xna.Framework.Vector2;
using Vector3 = Microsoft.Xna.Framework.Vector3;
using Matrix = Microsoft.Xna.Framework.Matrix;
namespace A.Namespace.Of.Your.Choice.Graphics
{
public sealed class PointBatch
{
private GraphicsDevice graphicsDevice;
private List<VertexPositionColor> points =
new List<VertexPositionColor>();
private VertexDeclaration vertexDeclaration;
private BasicEffect basicEffect;
private int pointSize;
public PointBatch( GraphicsDevice graphicsDevice, float alpha, int pointSize )
{
this.graphicsDevice = graphicsDevice;
basicEffect = new BasicEffect( graphicsDevice, null );
basicEffect.VertexColorEnabled = true;
basicEffect.Alpha = alpha;
basicEffect.Projection = Matrix.CreateOrthographicOffCenter( 0.0F,
graphicsDevice.Viewport.Width, graphicsDevice.Viewport.Height, 0.0F,
0.0F, -1.0F );
basicEffect.View = Matrix.Identity;
basicEffect.World = Matrix.Identity;
vertexDeclaration = new VertexDeclaration( graphicsDevice,
VertexPositionColor.VertexElements );
this.pointSize = pointSize;
}
public void Begin()
{
points.Clear();
}
public void Batch( Vector2 point, Color color )
{
VertexPositionColor batchPoint = new VertexPositionColor(
new Vector3( point, 0.0F ), color );
points.Add( batchPoint );
}
public void End()
{
if( points.Count > 0 )
{
graphicsDevice.VertexDeclaration = vertexDeclaration;
graphicsDevice.RenderState.PointSize = pointSize;
graphicsDevice.RenderState.FillMode = FillMode.Solid;
basicEffect.Begin();
foreach( EffectPass effectPass in basicEffect.CurrentTechnique.Passes )
{
effectPass.Begin();
graphicsDevice.DrawUserPrimitives<VertexPositionColor>(
PrimitiveType.PointList, points.ToArray(), 0, points.Count );
effectPass.End();
}
basicEffect.End();
}
}
}
}
The LineBatch...
using System.Collections.Generic;
using Microsoft.Xna.Framework.Graphics;
using Vector2 = Microsoft.Xna.Framework.Vector2;
using Vector3 = Microsoft.Xna.Framework.Vector3;
using Matrix = Microsoft.Xna.Framework.Matrix;
namespace A.Namespace.Of.Your.Choice.Graphics
{
public sealed class LineBatch
{
private GraphicsDevice graphicsDevice;
private List<VertexPositionColor> points =
new List<VertexPositionColor>();
private List<short> indices = new List<short>();
private VertexDeclaration vertexDeclaration;
private BasicEffect basicEffect;
public LineBatch( GraphicsDevice graphicsDevice, float alpha )
{
this.graphicsDevice = graphicsDevice;
basicEffect = new BasicEffect( graphicsDevice, null );
basicEffect.VertexColorEnabled = true;
basicEffect.Alpha = alpha;
basicEffect.Projection = Matrix.CreateOrthographicOffCenter( 0.0F,
graphicsDevice.Viewport.Width, graphicsDevice.Viewport.Height, 0.0F,
0.0F, -1.0F );
basicEffect.View = Matrix.Identity;
basicEffect.World = Matrix.Identity;
vertexDeclaration = new VertexDeclaration( graphicsDevice,
VertexPositionColor.VertexElements );
}
public void Begin()
{
points.Clear();
indices.Clear();
}
public void Batch( Vector2 startPoint, Vector2 endPoint,
Color color, float layerDepth )
{
Batch( startPoint, color, layerDepth );
Batch( endPoint, color, layerDepth );
}
public void Batch( Vector2 startPoint, Color startColor,
Vector2 endPoint, Color endColor, float layerDepth )
{
Batch( startPoint, startColor, layerDepth );
Batch( endPoint, endColor, layerDepth );
}
public void Batch( Vector2 point, Color color, float layerDepth )
{
VertexPositionColor batchPoint =
new VertexPositionColor(
new Vector3( point, layerDepth ), color );
points.Add( batchPoint );
indices.Add( ( short ) indices.Count );
}
public void End()
{
if( points.Count > 0 )
{
graphicsDevice.VertexDeclaration = vertexDeclaration;
graphicsDevice.RenderState.FillMode = FillMode.Solid;
basicEffect.Begin();
foreach( EffectPass effectPass in basicEffect.CurrentTechnique.Passes )
{
effectPass.Begin();
graphicsDevice.DrawUserIndexedPrimitives<VertexPositionColor>(
PrimitiveType.LineList, points.ToArray(), 0, points.Count,
indices.ToArray(), 0, points.Count / 2 );
effectPass.End();
}
basicEffect.End();
}
}
}
}
Hopefully at least one person might find them useful. As is where is. Any suggestions on improvements, bugs, etc welcome.
Cheers,
