Normally to clear the depth buffer between normal render passes, I do the following so that scene2 always renders in front of scene1:
renderer.render(scene1);
renderer.clearDepth();
renderer.render(scene2);
How do I do this with the effect composer renderPass?
composer.addPass(renderPass1);
// ??
composer.addPass(renderPass2);
I could use multiple composer instances per render pass and clear the depth buffer between their render calls but I might have to apply shaders to each composer instance that way unless I can copy the result of the first composer and use it in the second.