opengl Program Introspection Vertex Attribute Information
Example
Information about vertex attributes can be retrieved with the OGL function glGetProgram and the parameters GL_ACTIVE_ATTRIBUTES and GL_ACTIVE_ATTRIBUTE_MAX_LENGTH.
The location of an active shader attribute can be determined by the OGL function glGetAttribLocation, by the index of the attribute.
GLuint shaderProg = ...;
std::map< std::string, GLint > attributeLocation;
GLint maxAttribLen, nAttribs;
glGetProgramiv( shaderProg, GL_ACTIVE_ATTRIBUTES, &nAttribs );
glGetProgramiv( shaderProg, GL_ACTIVE_ATTRIBUTE_MAX_LENGTH, &maxAttribLen
GLint written, size;
GLenum type;
std::vector< GLchar >attrName( maxAttribLen );
for( int attribInx = 0; attribInx < nAttribs; attribInx++ )
{
glGetActiveAttrib( shaderProg, attribInx, maxAttribLen, &written, &size, &type, &attrName[0] );
attributeLocation[attrName] = glGetAttribLocation( shaderProg, attrName.data() );
}
