Solved get bitmap of shader in r20


I'm working on r20, and I found I can't use BaseShader::BakeShaderIntoBaseBitmap() because it is a new feature in r21. Trying find a way around, I want to extract the bitmap of the layer shader. However, my code does not work.

BaseBitmap* diffuseBitmap ;
GeData gd;
BaseShader* shader = bm->GetChannel(CHANNEL_DIFFUSION)->GetShader();

if (shader->GetType() == Xlayer) {
    LayerShader* layerShader = static_cast<LayerShader*>(shader); 
    LayerShaderLayer* layerShaderLayer = layerShader->GetFirstLayer();
    while (layerShaderLayer != NULL)
        if (layerShaderLayer->GetType() == LayerType::TypeShader)
	    Bool res = layerShaderLayer->GetParameter(LAYER_S_PARAM_SHADER_LINK, gd);

	    // diffuseBitmap = layerShaderLayer->GetPreview(); // this does not work, too!

	    BaseLink *bl = gd.GetBaseLink(); // program stop here, and I can't see why
	    BaseShader *thisShader = static_cast<BaseShader*>(bl->GetLinkAtom(bd));

	    diffuseBitmap = thisShader->GetBitmap();

	layerShaderLayer = layerShaderLayer->GetNext();
    // ...

ShowBitmap(diffuseBitmap); // can't see anything here when using 'layerShaderLayer->GetPreview()'
diffuseBitmap->Save(fn, FILTER_JPG, nullptr, SAVEBIT::NONE); // fail when using 'GetPreview()'

Could anyone kindly explain where I am doing wrong? Thanks a lot!


what is wrong with BaseShader::Sample? BakeShaderIntoBaseBitmap is probably only a convenience wrapper around that method. For your program "stoping" (this is a quite broad description), have you ensured, that your BaseLink is actually populated and does not just return the null pointer?


MAXON SDK Specialist

Thank you for your reply, the BaseShader::Sample() helps me solve this problem. (Except that when the layer shader use transform layer, scale transformation is not automatically handled.) Anyway, thanks a lot!

Hi @hazzzel thanks for reaching out us.

With regard to your question, please consider that you might have to attach a VolumeData to the InitRenderStruct.

For this scope please have a look at:

Best, R.