9/26/2023 0 Comments Triangle tessellation 128x128![]() This leaves 13 bits for the integer part = 8192 values. Let's assume that we need 8x8 subpixel precision for barycentric coordinates. But I would want to go as low as 16+16 bits if possible. 24 bit normalized integer would give exactly the same quality (in the range). Tomasz's technique is using 2x 32 bit floating point barycentric coordinates. Tomasz's technique is down to 96 bits per pixel. Result: Intel's technique is always 32 bits per pixel (no matter the scene complexity). ![]() Material id (if needed) can be added (SoA layout) to the visibility culling output. 16 million visible pieces of geometry (=4 billion visible rendered triangles) should be enough for everyone (at least for a while). Instead of using a global instance id, one should instead store a index to the culling output buffer (containing only visible clusters). This leaves 24 bits for the instance id, allowing us to draw 16 million independent pieces of geometry, or 8 instances per pixel (at 1080p). ![]() If we assume 256 triangle culling granularity, we can pack the triangle id inside the cluster in 8 bits. If the culling is based on constant sized sub-object pieces (clusters), there is a simple way to uniquely number the triangles. ![]() I will also assume that the renderer uses compute shaders to perform viewport and occlusion culling by sub-object granularity. Techniques 1 and 2 need 8 bytes to store instance id + triangle id in complex scenes (Intel is 32 bits in simple scenes).Īll of these techniques are perfect fit for GPU-driven pipelines, so I will assume that the geometry will be drawn by DirectX12 ExecuteIndirect or Vulkan MultiDrawIndirect. MSAA trick further reduces the G-buffer pixel shader wave count by ~3x and color bandwidth by ~2x, making it comparable to the Intel 32 bit per pixel technique in G-buffer bandwidth.įirst I will propose some improvements to techniques 1 and 2 to further reduce the G-buffer bandwidth cost of these techniques. Fetch the texture data in the lighting pass directly from the virtual texture cache (8k^2 texture atlas containing a grid of 128x128 texture pages - all currently visible surfaces guaranteed to be in the cache). Stores UV (16 + 16 bits) + tangent (32 bit encoded) instead of texture data. I was talking about this technique at SIGGRAPH 2015. Also there is no need to calculate the triangle intersection with the screen ray.ģ. With stored barycentric coordinates, you don't need to fetch the vertex positions from the memory (and transform the positions again). Similar to Intel's technique, but stores also barycentrics (2x32 bit) and instance id (32 bit). !115&app=PowerPoint&authkey=!AP-pDh4IMUug6vs Tomasz Stachowiak's "Deferred Material Rendering System" With transformed vertices and barycentrics interpolates per pixel values.Ģ. Intersects triangle by screen ray -> barycentrics. Runs "vertex shader" per pixel -> transformed vertices. 64 bit storage is needed if rendering scene with > 65536 instances AND max triangle count per mesh > 65536. Stores 32 bit packed triangle + instance id. (no matter how cheap the pixel shader is), as hierarchical depth culling saves considerable amount pixel shader invocations and bandwidth in complex scenes. However, you still need to render the depth buffer, as depth buffering during the rendering step is still a win Triangle id allows you to reconstruct the depth, so you don't need to read the depth buffer in the lighting step either. The smallest amount of data you need to store is a triangle id per pixel (32 bits). Instead of storing the uncompressed data to the g-buffer and reading the uncompressed data in the lighting step, these techniques directly sample the BC compressed data in the lighting shader (2x-4x reduction in texturing BW). Overdraw cost is minimized, resulting in less fluctuating frame rate.Īll of these techniques provide big saving in texture bandwidth. These techniques reduce the memory bandwidth usage by storing less data to the g-buffer and by only sampling the texture data for visible pixels. Lately several presentations, white papers and blog posts have been written about deferred rendering techniques that do not store any texture data to the g-buffer.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |