Amfs

Abstract

ReferenceMSAA A(MF)S AMFS 50k 0 Figure 1: Subdivision surfaces are widely used in offline rendering and an important tool for content creation. However, real-time rendering of tessellated geometry is still fairly expensive, as current pixel shading methods, e.g., multisampling antialiasing (MSAA), do not scale well with geometric complexity. With our method (AMFS), pixel shading is tied to the coarse input patches and reused between triangles, effectively decoupling the shading cost from the tessellation level, as shown in this example. AMFS can evaluate different parts of shaders at different frequencies, allowing very efficient shading. Our shading cost using a single shading frequency (middle right) is here 26% of that of MSAA (middle left), while the shading cost using multiple shading frequencies (far right) is only 7% of that of MSAA. AbstractWe propose a powerful hardware architecture for pixel shading, which enables flexible control of shading rates and automatic shading reuse between triangles in tessellated primitives. The main goal is efficient pixel shading for moderately to finely tessellated geometry, which is not handled well by current GPUs. Our method effectively decouples the cost of pixel shading from the geometric complexity. It thereby enables a wider use of tessellation and fine geometry, even at very limited power budgets. The core idea is to shade over small local grids in parametric patch space, and reuse shading for nearby samples. We also support the decomposition of shaders into multiple parts, which are shaded at different frequencies. Shading rates can be locally and adaptively controlled, in order to direct the computations to visually important areas and to provide performance scaling with a graceful degradation of quality. Another important benefit of shading in patch space is that it allows efficient rendering of distribution effects, which further closes the gap between real-time and offline rendering.