mesh.cs

using System;
using System.Runtime.InteropServices;
using OpenTK;
using OpenTK.Graphics.OpenGL;

namespace Template_P3 {

// mesh and loader based on work by JTalton; http://www.opentk.com/node/642

public class Mesh
{
	// data members
	public ObjVertex[] vertices;			// vertex positions, model space
	public ObjTriangle[] triangles;			// triangles (3 vertex indices)
	public ObjQuad[] quads;					// quads (4 vertex indices)
	int vertexBufferId;						// vertex buffer
	int triangleBufferId;					// triangle buffer
	int quadBufferId;						// quad buffer

	// constructor
	public Mesh( string fileName )
	{
		MeshLoader loader = new MeshLoader();
		loader.Load( this, fileName );
	}

	// initialization; called during first render
	public void Prepare( Shader shader )
	{
		if (vertexBufferId == 0)
		{
			// generate interleaved vertex data (uv/normal/position (total 8 floats) per vertex)
			GL.GenBuffers( 1, out vertexBufferId );
			GL.BindBuffer( BufferTarget.ArrayBuffer, vertexBufferId );
			GL.BufferData( BufferTarget.ArrayBuffer, (IntPtr)(vertices.Length * Marshal.SizeOf( typeof( ObjVertex ) )), vertices, BufferUsageHint.StaticDraw );

			// generate triangle index array
			GL.GenBuffers( 1, out triangleBufferId );
			GL.BindBuffer( BufferTarget.ElementArrayBuffer, triangleBufferId );
			GL.BufferData( BufferTarget.ElementArrayBuffer, (IntPtr)(triangles.Length * Marshal.SizeOf( typeof( ObjTriangle ) )), triangles, BufferUsageHint.StaticDraw );

			// generate quad index array
			GL.GenBuffers( 1, out quadBufferId );
			GL.BindBuffer( BufferTarget.ElementArrayBuffer, quadBufferId );
			GL.BufferData( BufferTarget.ElementArrayBuffer, (IntPtr)(quads.Length * Marshal.SizeOf( typeof( ObjQuad ) )), quads, BufferUsageHint.StaticDraw );
		}
	}

	// render the mesh using the supplied shader and matrix
	public void Render( Shader shader, Matrix4 transform, Matrix4 toWorld, Texture texture )
	{
		// on first run, prepare buffers
		Prepare( shader );

		// safety dance
		GL.PushClientAttrib( ClientAttribMask.ClientVertexArrayBit );

		// enable texture
		int texLoc = GL.GetUniformLocation( shader.programID, "pixels" );
		GL.Uniform1( texLoc, 0 );
		GL.ActiveTexture( TextureUnit.Texture0 );
		GL.BindTexture( TextureTarget.Texture2D, texture.id );

		// enable shader
		GL.UseProgram( shader.programID );

		// pass transform to vertex shader
		GL.UniformMatrix4( shader.uniform_mview, false, ref transform );
        GL.UniformMatrix4(shader.uniform_2wrld, false, ref toWorld);

        // enable position, normal and uv attributes
        GL.EnableVertexAttribArray( shader.attribute_vpos );
		GL.EnableVertexAttribArray( shader.attribute_vnrm );
		GL.EnableVertexAttribArray( shader.attribute_vuvs );

		// bind interleaved vertex data
		GL.EnableClientState( ArrayCap.VertexArray );
		GL.BindBuffer( BufferTarget.ArrayBuffer, vertexBufferId );
		GL.InterleavedArrays( InterleavedArrayFormat.T2fN3fV3f, Marshal.SizeOf( typeof( ObjVertex ) ), IntPtr.Zero );

		// link vertex attributes to shader parameters 
		GL.VertexAttribPointer( shader.attribute_vuvs, 2, VertexAttribPointerType.Float, false, 32, 0 );
		GL.VertexAttribPointer( shader.attribute_vnrm, 3, VertexAttribPointerType.Float, true, 32, 2 * 4 );
		GL.VertexAttribPointer( shader.attribute_vpos, 3, VertexAttribPointerType.Float, false, 32, 5 * 4 );

		// bind triangle index data and render
		GL.BindBuffer( BufferTarget.ElementArrayBuffer, triangleBufferId );
		GL.DrawArrays( PrimitiveType.Triangles, 0, triangles.Length * 3 );

		// bind quad index data and render
		if (quads.Length > 0)
		{
			GL.BindBuffer( BufferTarget.ElementArrayBuffer, quadBufferId );
			GL.DrawArrays( PrimitiveType.Quads, 0, quads.Length * 4 );
		}

		// restore previous OpenGL state
		GL.UseProgram( 0 );
		GL.PopClientAttrib();
	}

	// layout of a single vertex
	[StructLayout(LayoutKind.Sequential)] public struct ObjVertex
	{
		public Vector2 TexCoord;
		public Vector3 Normal;
		public Vector3 Vertex;
	}

	// layout of a single triangle
	[StructLayout(LayoutKind.Sequential)] public struct ObjTriangle
	{
		public int Index0, Index1, Index2;
	}

	// layout of a single quad
	[StructLayout(LayoutKind.Sequential)] public struct ObjQuad
	{
		public int Index0, Index1, Index2, Index3;
	}
}

} // namespace Template_P3