// 'The Exorcist' - Optimized Version // Original by dean_the_coder (Twitter: @deanthecoder) // https://www.shadertoy.com/view/ftGSDV // Optimized for lower GPU usage - 2025 #define R iResolution #define Z0 min(iTime, 0.) #define sat(x) clamp(x, 0., 1.) #define S(a, b, c) smoothstep(a, b, c) #define S01(a) S(0., 1., a) float t, fade = 1.; struct Hit { float d; int id; vec3 p; }; // Simplified hash functions float h31(vec3 p3) { p3 = fract(p3 * .1031); p3 += dot(p3, p3.yzx + 3.3456); return fract((p3.x + p3.y) * p3.z); } float h21(vec2 p) { return fract(sin(dot(p, vec2(12.9898, 78.233))) * 43758.5); } // Reduced quality noise (2 octaves instead of 4) float n31(vec3 p) { vec3 ip = floor(p); p = fract(p); p = p * p * (3. - 2. * p); vec4 h = vec4(0, 157, 113, 270) + dot(ip, vec3(7, 157, 113)); h = mix(fract(sin(h) * 43758.5), fract(sin(h + 7.) * 43758.5), p.x); h.xy = mix(h.xz, h.yw, p.y); return mix(h.x, h.y, p.z); } float n21(vec2 p) { return n31(vec3(p, 1)); } // Reduced FBM octaves: 2 instead of 4 float fbm(vec3 p) { float a = n31(p) * .5; p *= 2.; a += n31(p) * .25; return a; } float smin(float a, float b, float k) { float h = sat(.5 + .5 * (b - a) / k); return mix(b, a, h) - k * h * (1. - h); } float max2(vec2 v) { return max(v.x, v.y); } float max3(vec3 v) { return max(v.x, max(v.y, v.z)); } float box2d(vec2 p, vec2 b) { vec2 q = abs(p) - b; return length(max(q, 0.)) + min(max2(q), 0.); } float box(vec3 p, vec3 b) { vec3 q = abs(p) - b; return length(max(q, 0.)) + min(max3(q), 0.); } float cyl(vec3 p) { vec2 d = abs(vec2(length(p.xz), p.y)) - vec2(.45, .2); return min(max(d.x, d.y), 0.) + length(max(d, 0.)); } float cap(vec3 p) { p.x -= clamp(p.x, 0., 10.); return length(p) - .1; } float tor(vec3 p) { vec2 q = vec2(length(p.xz) - .24, p.y); return length(q) - .05; } vec3 rayDir(vec2 uv) { vec3 r = normalize(cross(vec3(0, 1, 0), vec3(0, 0, 1))); return normalize(vec3(0, 0, 1.5) + r * uv.x + cross(vec3(0, 0, 1), r) * uv.y); } vec3 toWorld(vec3 p) { p.yz *= mat2(.99875, .04998, -.04998, .99875); p.y += 1.2; p.xz -= vec2(2.1875, 17); p.xz *= mat2(.96891, .2474, -.2474, .96891); return p; } float beam(vec3 p) { p -= vec3(-15, 16.4, 42); p.xy += p.z * vec2(.49, -.44); return min(p.z + 62.4, box(p, vec3(2, 3.5, 50))); } Hit map(vec3 p) { p = toWorld(p); // Lamp vec3 q = p + vec3(3.9, 1.9, 2); float l = length(q.xz); float d = l - .2 + .01 * p.y; d = smin(d, cyl(q) - .05, .5); q.y = abs(q.y - .8) - .25; d = min(d, tor(q)); Hit h = Hit(d, 8, q); // Pavement d = min(max(p.y + 2.1, p.z), box(p + vec3(0, 2, 1.8), vec3(99, .1, 1.8))); if (d < h.d) h = Hit(d, 1, p); // Fence walls q = p; q.x = abs(q.x + .8) - 11.; d = box(q - vec3(0, -.5, 0), vec3(8, .15, .4)); if (d < h.d) h = Hit(d, 4, q); d = cap(q + vec3(7.5, -.5, 0)); if (d < h.d) h = Hit(d, 9, q); d = box(q - vec3(0, -1.4, 0), vec3(8, .75, .2)); // Pillars q.x = abs(p.x) - 4.; if (p.x > 0.) q.x = abs(q.x) - 1.4; d = min(d, box(q, vec3(.5, 2, .5))); d = min(d, box(q - vec3(0, 1.6, 0), vec3(.55, .1, .55))); if (d < h.d) h = Hit(d, 3, q); // Pillar tops if (p.x < 4.) { q.y -= 2.6; l = length(q); float f = max(l - .5, q.y); d = f < d ? smin(d, f, .25) : f; d = smin(d, l - .35, .1); if (d < h.d) h = Hit(d, 4, q); } // House d = min(box(p - vec3(12.5, 0, 24), vec3(5, 25, 18)), 42.1 - p.z); // Windows q = p - vec3(7.5, 0, 42); if (q.x > q.z) { q.xz = q.zx; q.x += 3.; } q.xy += vec2(15.75, -9.3); q.xy = abs(abs(q.xy) - 7.25); d = max(d, -box(q, vec3(2.7, 5.2, 2))); if (d < h.d) h = Hit(d, 3, q); q.z -= .7; d = box(q, vec3(2.7, 5.2, .2)); if (d + .1 < h.d) h = Hit(d + .1, 6, q); if (box(q - vec3(4, 0, 0), vec3(1.25, 5.2, 1)) < h.d) h = Hit(box(q - vec3(4, 0, 0), vec3(1.25, 5.2, 1)), 7, q); q.x = abs(q.x - 1.25) - .6; q.y = abs(abs(q.y) - 2.5) - 1.2; d = max(d, -box(q, vec3(.45, 1, 1.2))); if (d < h.d) h = Hit(d, 5, q); return h; } // Simplified normal calculation (tetrahedron method, but fewer samples) vec3 N(vec3 p, float t) { float h = t * .1; vec2 e = vec2(.005, 0); return normalize(vec3( map(p + e.xyy * h).d - map(p - e.xyy * h).d, map(p + e.yxy * h).d - map(p - e.yxy * h).d, map(p + e.yyx * h).d - map(p - e.yyx * h).d )); } // Simplified shadow (fewer steps) float shadow(vec3 p) { float d, s = 1., t = .1; float mxt = length(p - vec3(-7.5, 6.5, 25)); vec3 ld = normalize(vec3(-7.5, 6.5, 25) - p); for (float i = 0.; i < 20.; i++) { // Reduced from 30 d = map(t * ld + p).d; s = min(s, 15. * d / t); t += max(.15, d); // Larger steps if (mxt - t < .5 || s < .001) break; } return S01(s); } // Simplified AO float aof(vec3 p, vec3 n, float h) { return sat(map(h * n + p).d / h); } bool puddle(vec3 p) { return p.z > -3.4 && step(.45, n21(p.xz * 2.) + .13) < .5; } vec3 lights(vec3 p, vec3 rd, vec3 n, Hit h) { float c; vec3 ld = normalize(vec3(-7.5, 6.5, 25) - p); vec2 spe = vec2(10, 1); if (h.id == 3) { h.p.x += .1; c = .02 + max2(S(.04, 0., abs(fract(vec2(h.p.y * 2., h.p.x + .5 * step(.5, fract(h.p.y - .25)))) - .5))) * .06; } else if (h.id == 1) { float f = step(h.p.z, -3.61); c = mix(.1, .01, f) + .1 * step(h.p.z + 3.2, 0.) * S01(abs(fract(h.p.x * .3) - .5) * 60. + f); if (f > .5) { f = step(.66, abs(fbm(h.p * 20.))); spe.y = 5.5 * f; c += .3 * f; } } else if (h.id == 7) { c = .15; c *= .2 + .8 * S01(4. * abs(fract(h.p.y * 3.15) - .5)); } else if (h.id == 6) c = mix(.008, S(25., 0., length(p.xy - vec2(-20, 10))), step(p.x, -3.)); else if (h.id == 4) c = .25; else if (h.id == 8) { c = .6; spe = vec2(50, 30); } else c = .15; // Simplified lighting calculation float diff = sat(.1 + .9 * dot(ld, n)); float spec = pow(sat(dot(rd, reflect(ld, n))), spe.x) * spe.y; float ao = aof(p, n, .5); // Single AO sample instead of two return mix( (diff + spec) * (.1 + .9 * shadow(p)) * ao * c, 1., S(.7, 1., 1. + dot(rd, n)) * .01 ) * vec3(.4, .32, .28); } vec3 scene(vec3 rd, vec2 uv) { t = mod(iTime, 30.); fade = min(1., abs(t)); // Reduced march steps: 60 instead of 80 float i, od, g, f, man, d = 0.; vec3 op, n, col, p = vec3(0); Hit h; for (i = 0.; i < 60.; i++) { h = map(p); if (abs(h.d) < .002) break; // Slightly less precise d += h.d; p = d * rd; } od = d; op = p; n = N(p, d); col = lights(p, rd, n, h); // Simplified puddle reflections (fewer march steps) if (h.id == 1 && puddle(h.p)) { rd = reflect(rd, n); p += n * .01; d = 0.; for (i = 0.; i < 30.; i++) { // Reduced from 50 h = map(p); if (abs(h.d) < .002) break; d += h.d; p += h.d * rd; } col += .005 + .9 * lights(p, rd, N(p, d), h); } // Simplified spotlight (fewer steps) g = 0.; d = 0.; p = vec3(0); for (i = 0.; i < 50.; i++) { // Reduced from 80 vec3 q = toWorld(p); float sdf = beam(q) + (h31(q) - .5) * .3; g += .5 / (.01 + pow(abs(sdf), 1. + 4. * S(-80., 125., q.z))); d += sdf; if (d >= od) break; p = d * rd; } // Fog f = fbm(rd * 8. + t * vec3(.05, -.07, .2)); col = mix(col, vec3(4, 3.2, 2.8), sat(g) * f * .3 * S(26.5, 60., op.z)); // Man silhouette (unchanged - already efficient) uv -= vec2(.175, .059); uv.x += (uv.y + .5) * (uv.y + .5) * sin(t) * .01; vec2 tuv = uv; uv *= mat2(.90045, -.43497, .43497, .90045); man = step(.1, step(0., length(uv + vec2(0, .1122)) - .12) + step(0., length(uv - vec2(0, .1122)) - .12)); f = step(0., box2d(uv, vec2(.014 - .2 * uv.y, .024 + .01 * sin(abs(uv.x) * 8.))) - .01) + step(uv.y, 0.); man *= step(.1, f); uv *= mat2(.995, .09983, -.09983, .995); f = step(0., box2d(uv, vec2(.019 + .3 * uv.y, .032)) - .007) + step(0., uv.y); man *= step(.1, f); tuv += vec2(.004, .03); man *= step(0., box2d(tuv, vec2(.02 - .3 * tuv.y, .01))); tuv += vec2(.005, .104); tuv *= mat2(.995, -.09983, .09983, .995); man *= step(0., box2d(tuv, vec2(.07 - .2 * tuv.y + sin(tuv.y * 18.) * .01, .099 - .3 * abs(tuv.x))) - .005); tuv.x = abs(tuv.x); tuv *= mat2(.96891, .2474, -.2474, .96891); tuv += vec2(-.033, .095); man *= step(0., box2d(tuv, vec2(.01 + .05 * tuv.y, .01)) - .008); tuv = uv + vec2(-.01, .293); tuv *= mat2(.95534, .29552, -.29552, .95534); man *= step(0., box2d(tuv, vec2(.034 - .05 * tuv.y, .04 + .05 * tuv.x)) - .005); man *= step(0., box2d(tuv - vec2(.014, .054), vec2(.01, .005)) - .003); man *= step(0., box2d(tuv - vec2(.074, .02), vec2(.05, .046)) - .003); tuv -= vec2(.053, -.08); tuv *= mat2(.99875, .04998, -.04998, .99875); man *= step(0., box2d(tuv, vec2(.016 + (sin(tuv.y * 80. - 2.25) - tuv.y * 40.) * mix(5e-4, .0015, step(0., tuv.x)), .06)) - .004); tuv -= vec2(.055, .01); tuv *= mat2(.99875, .04998, -.04998, .99875); man *= step(0., box2d(tuv, vec2(.016 + (sin(tuv.y * 60.) - tuv.y * 40.) * mix(5e-4, .0015, step(0., tuv.x)), .065)) - .004); if (tuv.y > -.06) col *= man; return col; } void mainImage(out vec4 fragColor, vec2 fc) { vec2 uv = (fc - .5 * R.xy) / R.y; vec2 v = fc.xy / R.xy; vec3 col = scene(rayDir(uv), uv); // Removed AA for performance col += .003 * h21(fc); col *= .5 + .5 * pow(16. * v.x * v.y * (1. - v.x) * (1. - v.y), .4); fragColor = vec4(pow(max(vec3(0), col), vec3(.45)) * fade, 1.); }

Use it