Method Batcher

OpenCSG/src/batch.cpp:43–111

    };

    Batcher::Batcher(const std::vector<Primitive*>& primitives) { 

        FullscreenPrimitive fullscreen;

        const std::size_t numberOfPrimitives = primitives.size();
        mBatches.reserve(numberOfPrimitives);

        std::vector<Batch> batchCandidates;
        batchCandidates.reserve(numberOfPrimitives);

        for (std::vector<Primitive*>::const_iterator itr = primitives.begin(); itr != primitives.end(); ++itr) {

            // primitive completely outside viewport, no need to process it any further
            if (!Algo::intersectXY(*itr, &fullscreen))
                continue;

            // fullscreen is completely part of the primitive's bounding box,
            // no other primitive can be part of the same batch
            if (Algo::containsXY(&fullscreen, *itr)) {
                mBatches.push_back(Batch());
                Batch& batch = mBatches.back();
                batch.push_back(*itr);
            }
            else
            {
                std::vector<Batch>::iterator batchItr = batchCandidates.begin();
                std::vector<Batch>::iterator batchEnd = batchCandidates.end();

                for ( ; batchItr != batchEnd; ++batchItr) {

                    Batch & batch = *batchItr;
                    Batch::const_iterator batchPrimitives = batch.begin();
                    Batch::const_iterator batchPrimitivesEnd = batch.end();

                    // if the primitive does not intersect any of the primitives in
                    // the current batch, we can add the primitive to that batch
                    for ( ; batchPrimitives != batchPrimitivesEnd; ++batchPrimitives) {
                        if (Algo::intersectXY(*itr, *batchPrimitives)) {
                            break;
                        }
                    }
                    if (batchPrimitives == batchPrimitivesEnd) {
                        batch.push_back(*itr);
                        break;
                    }
                }

                // primitive could not added to any batch -> create a new batch
                if (batchItr == batchEnd) {
                    batchCandidates.push_back(Batch());
                    Batch& batch = batchCandidates.back();
                    batch.push_back(*itr);
                }
            }
        }

        // Could do here the following. But since since batchCandidates is not needed anymore,
        // we can use the std::vector swap trick to avoid calling of the copy constructor.