VBO Multiple texture coords

OpenGL Development
#1

Hey, I have a terrain made of 4 tiling textures(grass,dirt,metal,concrete) + one ‘mixmap’ as described in the top solution here: http://stackoverflow.com/questions/1110844/multiple-texture-images-blended-together-onto-3d-ground where the value of each channel(RGBA) corresponds to the alpha of the texture assigned to it (so red is the opacity of the grass texture at that pixel)

EVERYTHING works fine if I use the same texture coords for both. However, Since I want my ground textures to tile, and the mixmap to not tile (so top left corner of the map is texture coords 0,0 and bottom right is 1,1) I need to use separate texture coordinates for the map textures and the mixmap.

I am using an interleaved VBO. When I use gl_TexCoord[1].st, it doesn’t seem to work. For now I’m setting the second set of texture coords to have the same value as the first, but it’s not working.

Vertex Shader:


void main()
{
	gl_FrontColor = gl_Color;
	gl_Position = gl_ModelViewProjectionMatrix*gl_Vertex;
	gl_TexCoord[0]=gl_MultiTexCoord0;
	gl_TexCoord[1]=gl_MultiTexCoord1;
}

Fragment shader:


const int NUM_MAP_TEXTURES = 4;
uniform sampler2D maskTexture;
uniform sampler2D mapTextures[NUM_MAP_TEXTURES];
vec3 textureColours[NUM_MAP_TEXTURES];

void main()
{
	/*vec4 maskColour = vec4(texture2D(maskTexture, gl_TexCoord[1].st)); //gl_TexCoord[0]
	maskColour.a = 1 - maskColour.a;
	
	for(int i=0;i<NUM_MAP_TEXTURES;i++)
		textureColours[i] = vec3(texture2D(mapTextures[i], gl_TexCoord[0].st));
	
	vec3 finalColour = textureColours[0] * maskColour.r;
	for(int i=1;i<NUM_MAP_TEXTURES;i++)
		finalColour = mix(finalColour,  textureColours[i], maskColour[i]);
	
	gl_FragColor = vec4(finalColour, 1.0) * gl_Color;*/
	
	vec4 maskColour = vec4(texture2D(maskTexture, gl_TexCoord[1].st)); //gl_TexCoord[0].st 'works' but I need to use 1
	gl_FragColor = maskColour;
}

VBO creation:


int numTriangles = 2;
			int numVertices = numTriangles * 3;
			int vertexSize = (2 + 2 + 2)*4; //xy (2D) + texture COORDS(2 sets) only. NO COLOUR OR NORMALS //*4 for sizeof(float)
			FloatBuffer vertexData = BufferUtils.createFloatBuffer(vertexSize*numVertices);
			vertexData.put(new float[]{
					//Triangle 1
					-150,-150, 0,0,0,0, //0.2f,0.2f,
					150,-150, 1,0,1,0, //0.6f,0.2f,
					-150,150, 0,1,0,1,//0.2f,0.6f,
					
					//Triangle 2
					150,-150, 1,0,1,0, //0.6f,0.2f,
					-150,150, 0,1,0,1, //0.2f,0.6f,
					150,150, 1,1,1,1});  //0.6f,0.6f});
			vertexData.flip();
			vertexBufferData(vertexBufferID, vertexData);

Rendering:


//Bind shader [omitted]

GL11.glEnableClientState(GL11.GL_VERTEX_ARRAY);
GL11.glEnableClientState(GL11.GL_TEXTURE_COORD_ARRAY);
GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vertexBufferID);
			
int vertexSize = (2 + 2+ 2)*4; //xy + uv + uv2
int numVertices = 6;
			
GL11.glVertexPointer(2, GL11.GL_FLOAT, vertexSize/*stride*/, 0/*offset*/);


GL13.glActiveTexture(GL13.GL_TEXTURE0);
GL11.glTexCoordPointer(2, GL11.GL_FLOAT, vertexSize/*stride*/, 2*4/*offset*/);

int sampler=ARBShaderObjects.glGetUniformLocationARB(shader.GetShaderID(), "mapTextures[0]");
GL11.glBindTexture(GL11.GL_TEXTURE_2D, textures[0].GetTextureID());
ARBShaderObjects.glUniform1iARB(sampler, 0);



GL13.glActiveTexture(GL13.GL_TEXTURE1);
GL11.glTexCoordPointer(2, GL11.GL_FLOAT, vertexSize/*stride*/, (2+2)*4/*offset*/);
sampler=ARBShaderObjects.glGetUniformLocationARB(shader.GetShaderID(), "maskTexture");
GL11.glBindTexture(GL11.GL_TEXTURE_2D, mixMapTexture.GetTextureID());
ARBShaderObjects.glUniform1iARB(sampler, 1);

GL13.glActiveTexture(GL13.GL_TEXTURE0);

GL11.glDrawArrays(GL11.GL_TRIANGLES, 0, numVertices);

GL11.glDisableClientState(GL11.GL_VERTEX_ARRAY);
GL11.glDisableClientState(GL11.GL_TEXTURE_COORD_ARRAY);


//Unbind shader [omitted]

Ouput using vec4 maskColour = vec4(texture2D(maskTexture, gl_TexCoord[0].st));
NB my mixmap texture has 4 bars of colour: 1,0,0,1 0,1,0,1 0,0,1,1 0,0,0,0

Ouput using vec4 maskColour = vec4(texture2D(maskTexture, gl_TexCoord[1].st));

However if I change the mixmap image colour to full green, it will show a full green rectangle. I’m thinking that the 2nd set of texture coords just doesn’t work at all and they are all set to (0,0) or something.

Can anyone help me figure this out?
Thanks,
roland