Requested improvements to OpenGL shader support in JUCE

General JUCE discussion
2

Hi all,

I’d really like to get some feedback on this. I see that since my post, others have had the same problem (see here) in addition to previous requests by others (here & here).

To elaborate on where I’ve got to, I’ve found a workable solution now with very few changes to the JUCE codebase. In OpenGLGraphicsContextCustomShader I have added a public member:

std::function<void(OpenGLShaderProgram*)> onSetUniforms;

then in ShaderBase I have added one of these also.

Then in OpenGLGraphicsContextCustomShader::fillRect I have added a copy of the std::function - I actually hate this bit and would remove it but I have no idea of the lifetime of objects in this part of JUCE, so a better solution should be found for this…

if (OpenGLRendering::ShaderContext* sc = dynamic_cast<OpenGLRendering::ShaderContext*> (&gc))
        if (CustomProgram* c = CustomProgram::getOrCreate (gc, hashName, code, errorMessage))
        {
            c->onSetUniforms = onSetUniforms;
            sc->fillRectWithCustomShader (*c, area);
        }

Finally, in CurrentShader::setShader I have added the following after the call to shader.bindAttributes (context);:

if (shader.onSetUniforms)
    shader.onSetUniforms (&shader.program);

This allows me to use a lambda to set uniforms and do other things at this point, e.g.

shader->onSetUniforms = [&](OpenGLShaderProgram* program)
{
     program->setUniform ("myUniform", 0.5f);                    
};

I am doing this successfully with several uniforms and passing textures to shaders. They render in a way that integrates nicely with other JUCE components.

I can totally see that some other solution might be better - perhaps some virtual function in OpenGLGraphicsContextCustomShader such as…

virtual void setUniforms (OpenGLShaderProgram* program);

that we could override. But in general, it feels like this is something lots of people keep coming back to and I think a solution to it wouldn’t be too much work (unless I’m overlooking something).

Looking forward to your thoughts,

Adam

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