VulkanLearn2 ReSTIR DI & GI & PT 1spp ReSTIR PT without accumulation Goals improve shading model improve ReSTIR Neural Radiance Cache accelaration Simple Denoiser Comparison classic path tracer with NEE and ReSTIR PT 1 spp without accumulation Referense Pathtracer from RaytracerGems 2 with emissive triangle and NEE RIS support Restir PT with emissive triangle