Function subtractPrimitives

OpenCSG/src/renderSCS.cpp:520–605

        }

        void subtractPrimitives(const std::vector<Batch>& batches,
                                const unsigned int depthComplexity = 0) {

            int setting = getOption(CameraOutsideOptimization);
            bool cameraInsideModel = (setting == OptimizationOff);

            glStencilMask(OpenGL::stencilMask);
            glEnable(GL_STENCIL_TEST);
            glEnable(GL_CULL_FACE);

            size_t numberOfBatches = batches.size();
            BouncingSequencer bounce(numberOfBatches);
            SchoenfieldSequencer schoenfield(numberOfBatches);
            Sequencer * sequencer = 0;
            size_t numIterations;
            if (depthComplexity == 0)
            {
                sequencer = &schoenfield;
                numIterations = sequencer->size();
            }
            else
            {
                sequencer = &bounce;
                numIterations = sequencer->sizeForDepthComplexity(depthComplexity);
            }

            unsigned int stencilref = 0;
            for (size_t i = 0; i < numIterations; ++i)
            {
                const Batch& batch = batches[sequencer->index(i)];

                // create a distinct reference value
                ++stencilref;
                if (stencilref == OpenGL::stencilMax) {
                    glClear(GL_STENCIL_BUFFER_BIT);
                    stencilref = 1;
                }

                channelMgr->renderToChannel(false);

                glDepthMask(GL_FALSE );
                glStencilFunc(GL_ALWAYS, stencilref, OpenGL::stencilMask);
                glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);

                if (cameraInsideModel)
                {
                    glDepthFunc(GL_GREATER);
                    glCullFace(GL_FRONT);

                    for (Batch::const_iterator j = batch.begin(); j != batch.end(); ++j) {
                        (*j)->render();
                    }

                    glStencilFunc(GL_EQUAL, stencilref, OpenGL::stencilMask);
                    glStencilOp(GL_ZERO, GL_ZERO, GL_KEEP);
                }

                glDepthFunc(GL_LESS);