I have drawn a triangle and a square using open gl and everything was fine.
I have then tried to draw the same triangle and square, while implementing VAO's and now I only get a white triangle - that is not the triangle I am attempting to draw. As far as I can see I am binding everything correctly in the onLoad method.
The square doesnt draw at all. Only the triangle which is not right.
If anyone could point out what I am missing or point me to somewhere I can understand this problem and fix (tutorial or other documentation) I would be very grateful.
Here is the code
using Labs.Utility;
using OpenTK;
using OpenTK.Graphics;
using OpenTK.Graphics.OpenGL;
using System;
namespace Labs.Lab2
{
class Lab2_1Window : GameWindow
{
private int[] mVertexArrayObjectIDs = new int[2];
private int[] mTriangleVertexBufferObjectIDArray = new int[2];
private int[] mSquareVertexBufferObjectIDArray = new int[2];
private ShaderUtility mShader;
public Lab2_1Window()
: base(
800, // Width
600, // Height
GraphicsMode.Default,
"Lab 2_1 Linking to Shaders and VAOs",
GameWindowFlags.Default,
DisplayDevice.Default,
3, // major
3, // minor
GraphicsContextFlags.ForwardCompatible
)
{
}
protected override void OnLoad(EventArgs e)
{
GL.ClearColor(Color4.CadetBlue);
GL.Enable(EnableCap.DepthTest);
#region Shader Loading Code
mShader = new ShaderUtility(@"Lab2/Shaders/vLab21.vert", @"Lab2/Shaders/fSimple.frag");
#endregion
int vColourLocation = GL.GetAttribLocation(mShader.ShaderProgramID, "vColour");
int vPositionLocation = GL.GetAttribLocation(mShader.ShaderProgramID, "vPosition");
//square
float[] sVertices = new float[] { -0.2f, -0.4f, 0.2f, 0.0f, 1.0f, 0.2f,
0.8f, -0.4f, 0.2f, 0.0f, 1.0f, 1.0f,
0.8f, 0.6f, 0.2f, 0.0f, 1.0f, 0.4f,
-0.2f, 0.6f, 0.2f, 0.0f, 1.0f, 0.0f};
uint[] sIndices = new uint[] { 0, 1, 2,
0,3,2};
GL.GenVertexArrays(2, mVertexArrayObjectIDs);
GL.BindVertexArray(mVertexArrayObjectIDs[1]);
GL.GenBuffers(2, mSquareVertexBufferObjectIDArray);
GL.BindBuffer(BufferTarget.ArrayBuffer, mSquareVertexBufferObjectIDArray[0]);
GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(sVertices.Length * sizeof(float)), sVertices, BufferUsageHint.StaticDraw);
int sSize;
GL.GetBufferParameter(BufferTarget.ArrayBuffer, BufferParameterName.BufferSize, out sSize);
if (sVertices.Length * sizeof(float) != sSize)
{
throw new ApplicationException("Vertex data not loaded onto graphics card correctly");
}
GL.BindBuffer(BufferTarget.ElementArrayBuffer, mSquareVertexBufferObjectIDArray[1]);
GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(sIndices.Length * sizeof(int)), sIndices, BufferUsageHint.StaticDraw);
GL.GetBufferParameter(BufferTarget.ElementArrayBuffer, BufferParameterName.BufferSize, out sSize);
if (sIndices.Length * sizeof(int) != sSize)
{
throw new ApplicationException("Index data not loaded onto graphics card correctly");
}
GL.VertexAttribPointer(vPositionLocation, 3, VertexAttribPointerType.Float, false, 6 *
sizeof(float), 0);
GL.VertexAttribPointer(vColourLocation, 3, VertexAttribPointerType.Float, false, 6 *
sizeof(float), 3 * sizeof(float));
//GL.EnableVertexAttribArray(vColourLocation);
//GL.EnableVertexAttribArray(vPositionLocation);
//triangle
float[] tVertices = new float[] { -0.8f, 0.8f, 0.4f, 1.0f, 0.0f, 0.6f,
-0.6f, -0.4f, 0.4f, -0.2f, 0.5f, 1.0f,
0.2f, 0.2f, 0.4f, -1.0f, 0.0f, 1.0f};
uint[] tIndices = new uint[] { 0, 1, 2 };
//GL.GenVertexArrays(2, mVertexArrayObjectIDs);
GL.BindVertexArray(mVertexArrayObjectIDs[0]);
GL.GenBuffers(2, mTriangleVertexBufferObjectIDArray);
GL.BindBuffer(BufferTarget.ArrayBuffer, mTriangleVertexBufferObjectIDArray[0]);
GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(tVertices.Length * sizeof(float)), tVertices, BufferUsageHint.StaticDraw);
int size;
GL.GetBufferParameter(BufferTarget.ArrayBuffer, BufferParameterName.BufferSize, out size);
if (tVertices.Length * sizeof(float) != size)
{
throw new ApplicationException("Vertex data not loaded onto graphics card correctly");
}
GL.BindBuffer(BufferTarget.ElementArrayBuffer, mTriangleVertexBufferObjectIDArray[1]);
GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(tIndices.Length * sizeof(int)), tIndices, BufferUsageHint.StaticDraw);
GL.GetBufferParameter(BufferTarget.ElementArrayBuffer, BufferParameterName.BufferSize, out size);
if (tIndices.Length * sizeof(int) != size)
{
throw new ApplicationException("Index data not loaded onto graphics card correctly");
}
GL.VertexAttribPointer(vPositionLocation, 3, VertexAttribPointerType.Float, false, 6 *
sizeof(float), 0);
GL.VertexAttribPointer(vColourLocation, 3, VertexAttribPointerType.Float, false, 6 *
sizeof(float), 3 * sizeof(float));
GL.EnableVertexAttribArray(vColourLocation);
GL.EnableVertexAttribArray(vPositionLocation);
base.OnLoad(e);
}
protected override void OnRenderFrame(FrameEventArgs e)
{
base.OnRenderFrame(e);
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
GL.BindVertexArray(mVertexArrayObjectIDs[1]);
GL.DrawElements(PrimitiveType.Triangles, 6, DrawElementsType.UnsignedInt, 0);
GL.BindVertexArray(mVertexArrayObjectIDs[0]);
GL.DrawElements(PrimitiveType.Triangles, 3, DrawElementsType.UnsignedInt, 0);
GL.BindVertexArray(0);
this.SwapBuffers();
}
protected override void OnUnload(EventArgs e)
{
base.OnUnload(e);
GL.BindVertexArray(0);
GL.DeleteVertexArrays(2, mVertexArrayObjectIDs);
GL.DeleteBuffers(2, mTriangleVertexBufferObjectIDArray);
GL.DeleteBuffers(2, mSquareVertexBufferObjectIDArray);
GL.UseProgram(0);
mShader.Delete();
}
}
}
EDIT: 
