When a ray collides with geometry defined by the depth buffer, the shader calculates how light should scatter or reflect.
: Enhanced in the 2021 updates, this allowed the ray tracing to reach further into the scene, improving the accuracy of long-distance shadows and ambient occlusion. Image-Based Lighting (IBL)
Traditional video game graphics utilize pre-baked lighting maps or screen-space ambient occlusion (SSAO) to simulate depth and shadow. While fast, these methods cannot calculate true indirect lighting—such as a bright red wall casting a warm pink glow onto a white marble floor. How RTGI Works
Unlike native RTX ray tracing, RTGI does not require specialized hardware (like RT cores) and can run on any powerful GPU, including older non-RTX cards. Global Illumination:
If you want to breathe new life into older games, Pascal Gilcher’s Ray Traced Global Illumination (RTGI) shader for ReShade is the gold standard. Version 0.33, released in 2021, remains a milestone for its balance of performance and visual fidelity.
The RTGI 0.33 shader files (historically distributed via Pascal Gilcher's Patreon). 2. File Placement
Using RTGI requires a standard ReShade installation and access to Pascal Gilcher's shader files.
The year 2021 marked a massive turning point for this software ecosystem. The community witnessed major optimizations across the alpha and beta branches, leading directly to highly anticipated iterations like . Understanding ReShade RTGI
: Uses a specialized spatio-temporal filter to smooth out graininess caused by real-time ray calculations.
Always keep this enabled. It cleans up the visual noise from lower Ray/Step counts without introducing ghosting artifacts. Limitations of Screen-Space Ray Tracing
