forge-hdr-tone-mapping

HDR tone mapping in SDL GPU requires a two-pass pipeline: render the scene to a floating-point HDR target, then apply Reinhard or ACES tone-mapping shaders to output to the swapchain. This preserves bright highlights and achieves a filmic look.

Reinhard and ACES are both configurable tone-mapping operators for HDR rendering. Reinhard offers a simpler dynamic range compression, while ACES provides a filmic look with better color rolloff in highlights. Both support exposure control to adjust scene brightness.

Yes, a floating-point HDR render target is required for tone mapping in SDL GPU. The scene must first render to this target to capture high dynamic range values, then a separate post-processing pass applies the tone-mapping shader to convert the image for the swapchain.

Exposure control adjusts the brightness of the HDR scene before the ACES tone-mapping operator processes it. This configurable step happens during the post-processing pass, allowing flexible adjustment of the final filmic look when converting the floating-point target to the swapchain.

HDR rendering pipelines require a clear separation between scene and post-processing passes to handle resize events and sRGB swapchains correctly. The floating-point HDR render target must be resized alongside the swapchain, and tone-mapping shaders must output to the correct sRGB format.

Bright highlights clip when rendering directly to an SDR swapchain without HDR tone mapping. Implementing a two-pass pipeline with a floating-point render target and Reinhard or ACES tone-mapping preserves detail in bright areas and produces correct filmic results.