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averron82

OpenGL Using Vertex Array Objects With Cg Shaders

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I'm writing an application which uses OpenGL vertex array objects and Cg shaders, however I'm having difficulty getting the latter to read texture coordinates from the former.

The weird thing is, the exact same VAO works fine with a GLSL shader, whilst the Cg shader works fine with legacy OpenGL calls (glTexCoord2f etc.)

The code used to create a vertex array object is shown below:

float vertices[12] = {-0.5f, -0.5f, -0.5f, 0.5f, -0.5f, -0.5f, 0.5f, 0.5f, -0.5f, -0.5f, 0.5f, -0.5f};

float texCoords[8] = {0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f};

// Create and bind the VAO to store the square.
glGenVertexArrays(1, &vao[0]);
glBindVertexArray(vao[0]);

glGenBuffers(2, vbo);

// Vertex VBO.
glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
glBufferData(GL_ARRAY_BUFFER, 12 * sizeof(GLfloat), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), 0);
glEnableVertexAttribArray(0);

// Texture VBO.
glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(GLfloat), texCoords, GL_STATIC_DRAW);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(GLfloat), 0);
glEnableVertexAttribArray(1);

glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);


The Cg vertex shader:

struct OUTPUTv
{
float4 position : POSITION;

float2 texCoord : TEXCOORD0;
};

OUTPUTv mainV(in float4 position : POSITION, in float2 texCoord : TEXCOORD0, uniform float4x4 modelviewproj)
{
OUTPUTv OUT;

OUT.position = mul(modelviewproj, position);

OUT.texCoord = texCoord;

return OUT;
}


The Cg fragment shader:

struct OUTPUTf
{
float4 color : COLOR;
};

OUTPUTf mainF(in float2 texCoord : TEXCOORD0, uniform sampler2D diffuseMap : TEX0)
{
OUTPUTf OUT;

OUT.color = tex2D(diffuseMap, texCoord);

return OUT;
}


Any advice would be appreciated, thanks!

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