Adding support for shaders to OCCT visualization toolkit

The purpose of this feature is adding support of GLSL shaders to OCCT visualization core. Shaders allow to implement different rendering effects on graphics hardware with a high degree of flexibility, such as per-pixel lighting, custom shading models, bump mapping, procedural texturing and others. Currently OCCT supports only vertex and fragment GLSL shader, but this functionality will be extended in future releases.


To set custom vertex and fragment GLSL shaders in DRAW the following command is used:

vshaderprog <ShapeName> <Path to Vertex Shader> <Path to Fragment Shader>

To detach shader program from specific shape, use the following command:

vshaderprog <ShapeName> off

Note, that to execute shader programs the OpenGL 2.0+ GPU is required.


To enable custom shader for specific AISShape in your application, the following API functions are used:

// Create shader program
Handle(Graphic3d_ShaderProgram) aProgram = new Graphic3d_ShaderProgram();

// Attach vertex shader
aProgram->AttachShader (Graphic3d_ShaderObject::CreateFromFile(
                               Graphic3d_TOS_VERTEX, "<Path to VS>"));

// Attach fragment shader
aProgram->AttachShader (Graphic3d_ShaderObject::CreateFromFile(
                               Graphic3d_TOS_FRAGMENT, "<Path to FS>"));

// Set values for custom uniform variables (if they are)
aProgram->PushVariable ("MyColor", Graphic3d_Vec3(0.f, 1.f, 0.f));

// Set aspect property for specific AISShape
AISShape->Attributes()->ShadingAspect()->Aspect()->SetShaderProgram (aProgram);