ps4tw said:
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Yes, they did. I remember being fascinated with the effect in Unreal and experimenting with it myself in Open GL/Direct X when I was learning 3D graphics programming.
<- programmer
One of the first rooms you enter in Unreal has spherical volume lighting, and Quake 3 had similar with fog volumes. Ray tracing vertices or fog maps to surfaces from the eye through an arbitrary convex volume (mostly spheres to keep performance acceptable back then) to determine line segment length through the light/fog volume, and attenuating for distance from center of the volume, to set the color/alpha intensity then rendering an additional pass to any surface in or behind the fog volume.
Unreal's technique is a little more refined. IIRC Quake 3 just used tessellated vertices and vertex shading while Unreal actually used low res view dependant fog textures similar to light maps that were raytaced per pixel per frame then applied with multi texture or an additional rendering pass with blending enabled. It came out much smoother than Quake 3 which suffered from mach banding and tessellation issues since it was per vertex.
View dependent real time volumetric lighting is a VERY old effect. I was absolutely fascinated by it in the 90s.













