Today, I wrote a shader for foveated rendering uisng Prof. Neyret’s QuadTree: https://www.shadertoy.com/view/Ml3SDf
The basic idea is:
- Calculate the depth of the QuadTree using the distance between the current coordinate to the foveat region
- Use the depth as the mipmap level to sample from the texture
Code below:
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// forked and remixed from Prof. Neyret's https://www.shadertoy.com/view/ltBSDV // Foveated Rendering via Quadtree: https://www.shadertoy.com/view/Ml3SDf# void mainImage( out vec4 o, vec2 U ) { float r = 0.1, t = iGlobalTime, H = iResolution.y; vec2 V = U.xy / iResolution.xy; U /= H; // foveated region : disc(P,r) vec2 P = .5 + .5 * vec2(cos(t), sin(t * 0.7)), fU; U *= .5; P *= .5; // unzoom for the whole domain falls within [0,1]^n float mipmapLevel = 4.0; for (int i = 0; i < 7; ++i) { // to the infinity, and beyond ! :-) //fU = min(U,1.-U); if (min(fU.x,fU.y) < 3.*r/H) { o--; break; } // cell border if (length(P - vec2(0.5)) - r > 0.7) break; // cell is out of the shape // --- iterate to child cell fU = step(.5, U); // select child U = 2.0 * U - fU; // go to new local frame P = 2.0 * P - fU; r *= 2.0; mipmapLevel -= 0.5; } o = texture2D(iChannel0, V, mipmapLevel); } |
