GLSL Attributes: tangent and binormal

OpenGL
1

Hi,

I have this problem:

At the moment I using RenderMonkey to do some GLSL shader programs. In RenderMonkey the Tangent and Binormal for every vertex is given by:

attribute vec3 rm_Tangent;
attribute vec3 rm_Binormal;

I’m implementing this in Opengl.
At the moment I can calculate the Tangent and Binormal for every vertex, but How Do I Pass This Values To The Shader Program in OPENGL???

I know passing Uniforms and samplers in OpenGL can be done like this:

// Send Uniforms and samplers
glUseProgramObject(shaderProgram);
int myColor3f_Location = glGetUniformLocation(shaderProgram, “myColor3f”);
glUniform3f(myColor3f_Location, 1.0f, 0.5f, 0.2f);

int mySampler2D_Location = glGetUniformLocation(shaderProgram, “mySampler2D”);
glActiveTexture(GL_TEXTURE0); // MultiTexture activate Texture0
glBindTexture(GL_TEXTURE_2D, texture[0]);
glUniform1i(mySampler2D_Location, 0);

But how do I send Attributes??

Thanks.

2

You can either pass them by using texture coordinates (glMultiTexCoord) or by using glVertexAttrib{1234}{bsifd ubusui}. See http://oss.sgi.com/projects/ogl-sample/registry/ARB/vertex_shader.txt chapter 2.7 for more details.

3

Write something like this:
float *m_pT; // Array of Tangents

glEnableVertexAttribArrayARB(6); // use 7 for binormals

glVertexAttribPointerARB(6, 3, GL_FLOAT, GL_FALSE, 0, m_pT);

glBindAttribLocationARB(ProgramObject, 6, “rm_Tangent”);

glLinkProgramARB(ProgramObject);

Don’t forget to Link the program AFTER doing the glBindAttribLocationARB.

4

There was also this extension:

GL_EXT_coordinate_frame (published back to 1998 !)

With two new functions:

glBinormalPointerEXT
glTangentPointerEXT

But actually no video card supports it (due to patents issues)

5

Thanks Everyone!

6

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