Why doesn't my texture display with this GLSL shader?
- by Chewy Gumball
I am trying to display a DXT1 compressed texture on a quad using a VBO and shaders, but I have been unable to get it working. All I get is a black square.
I know my texture is uploaded properly because when I use immediate mode without shaders the texture displays fine but I will include that part just in case. Also, when I change the gl_FragColor to something like vec4 (0.0, 1.0, 1.0, 1.0) then I get a nice blue quad so I know that my shader is able to set the colour. It appears to be either the texture is not being bound correctly in the shader or the texture coordinates are not being picked up. However, I can't find the error! What am I doing wrong?
I am using OpenTK in C# (not xna).
Vertex Shader:
void main() {
gl_TexCoord[0] = gl_MultiTexCoord0;
// Set the position of the current vertex
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}
Fragment Shader:
uniform sampler2D diffuseTexture;
void main() {
// Set the output color of our current pixel
gl_FragColor = texture2D(diffuseTexture, gl_TexCoord[0].st);
//gl_FragColor = vec4 (0.0,1.0,1.0,1.0);
}
Drawing Code:
int vb, eb;
GL.GenBuffers(1, out vb);
GL.GenBuffers(1, out eb);
// Position Texture
float[] verts = { 0.1f, 0.1f, 0.0f, 0.0f, 0.0f,
1.9f, 0.1f, 0.0f, 1.0f, 0.0f,
1.9f, 1.9f, 0.0f, 1.0f, 1.0f,
0.1f, 1.9f, 0.0f, 0.0f, 1.0f
};
uint[] indices = {
0, 1, 2,
0, 2, 3
};
//upload data to the VBO
GL.BindBuffer(BufferTarget.ArrayBuffer, vb);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, eb);
GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(verts.Length * sizeof(float)), verts, BufferUsageHint.StaticDraw);
GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(indices.Length * sizeof(uint)), indices, BufferUsageHint.StaticDraw);
//Upload texture
int buffer = GL.GenTexture();
GL.BindTexture(TextureTarget.Texture2D, buffer);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (float)TextureWrapMode.Repeat);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (float)TextureWrapMode.Repeat);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (float)TextureMagFilter.Linear);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (float)TextureMinFilter.Linear);
GL.TexEnv(TextureEnvTarget.TextureEnv, TextureEnvParameter.TextureEnvMode, (float)TextureEnvMode.Modulate);
GL.CompressedTexImage2D(TextureTarget.Texture2D, 0, texture.format, texture.width, texture.height, 0, texture.data.Length, texture.data);
//Draw
GL.UseProgram(shaderProgram);
GL.EnableClientState(ArrayCap.VertexArray);
GL.EnableClientState(ArrayCap.TextureCoordArray);
GL.VertexPointer(3, VertexPointerType.Float, 5 * sizeof(float), 0);
GL.TexCoordPointer(2, TexCoordPointerType.Float, 5 * sizeof(float), 3);
GL.ActiveTexture(TextureUnit.Texture0);
GL.Uniform1(GL.GetUniformLocation(shaderProgram, "diffuseTexture"), 0);
GL.DrawElements(BeginMode.Triangles, indices.Length, DrawElementsType.UnsignedInt, 0);
