precision highp float; uniform float time; uniform vec2 mouse; uniform vec2 resolution; struct Surface { float t; vec3 pos; vec3 nor; vec3 diffColor; vec3 specColor; float diff; float spec; }; #define GROUND_WIDTH 10.0 #define SPHERE_NUM 9 float SPHERE_RADIUSES[SPHERE_NUM]; vec3 SPHERE_POSITIONS[SPHERE_NUM]; void initConstants() { SPHERE_RADIUSES[0] = 3.0; SPHERE_RADIUSES[1] = 0.8; SPHERE_RADIUSES[2] = 1.2; SPHERE_RADIUSES[3] = 1.0; SPHERE_RADIUSES[4] = 0.7; SPHERE_RADIUSES[5] = 1.2; SPHERE_RADIUSES[6] = 0.6; SPHERE_RADIUSES[7] = 0.9; SPHERE_RADIUSES[8] = 1.0; SPHERE_POSITIONS[0] = vec3(0.0, SPHERE_RADIUSES[0], 0.0); SPHERE_POSITIONS[1] = vec3(3.2, SPHERE_RADIUSES[1], 2.8); SPHERE_POSITIONS[2] = vec3(-2.5, SPHERE_RADIUSES[2], 3.4); SPHERE_POSITIONS[3] = vec3(3.0, SPHERE_RADIUSES[3], -2.5); SPHERE_POSITIONS[4] = vec3(-3.0, SPHERE_RADIUSES[4], -2.5); SPHERE_POSITIONS[5] = vec3(1.0, 4.0, 4.3); SPHERE_POSITIONS[6] = vec3(-3.4, 5.2, 0.5); SPHERE_POSITIONS[7] = vec3(-0.9, 2.4, -4.5); SPHERE_POSITIONS[8] = vec3(4.7, 3.4, -0.9); } float mapSpheres(vec3 p) { float d = 1e8; for (int i = 0; i < SPHERE_NUM; i++) { d = min(d, length(p - SPHERE_POSITIONS[i]) - SPHERE_RADIUSES[i]); } return d; } float mapGround(vec3 p, float width) { p.xz = abs(p.xz) - 0.5 * width; return length(max(p, 0.0)) + min(max(p.x, max(p.y, p.z)), 0.0); } float map(vec3 p) { float ds = mapSpheres(p); float dg = mapGround(p, GROUND_WIDTH); return min(ds, dg); } float ambientOcclusion(vec3 p, vec3 n, float step) { float ao = 1.0; float amp = 0.5; for (float i = 1.0; i <= 5.0; i += 1.0) { float t = i * step; float d = max(0.0, map(p + t * n)); ao -= amp * (t - d) / t; amp *= 0.5; } return ao; } bool hitSphere(vec3 ro, vec3 rd, float r, vec3 offset, inout Surface surf) { ro -= offset; float a = dot(rd, rd); float b = 2.0 * dot(ro, rd); float c = dot(ro, ro) - r * r; float d = b * b - 4.0 * a * c; if (d < 0.0) { return false; } float sqrtD = sqrt(d); float t = (-b - sqrtD) / (2.0 * a); if (t > 0.0 && t < surf.t) { surf.t = t; surf.pos = ro + offset + t * rd; surf.nor = normalize(ro + t * rd); return true; } return false; } void hitGround(vec3 ro, vec3 rd, float width, inout Surface surf) { bool hit = false; float hw = 0.5 * width; float ty = -ro.y / rd.y; if (ty > 0.0 && ty < surf.t) { vec3 p = ro + ty * rd; if (abs(p.x) < hw && abs(p.z) < hw) { hit = true; surf.t = ty; surf.pos = p; surf.nor = vec3(0.0, 1.0, 0.0); } } float tpx = (hw - ro.x) / rd.x; if (tpx > 0.0 && tpx < surf.t) { vec3 p = ro + tpx * rd; if (p.y < 0.0 && abs(p.z) < hw) { hit = true; surf.t = tpx; surf.pos = p; surf.nor = vec3(1.0, 0.0, 0.0); } } float tmx = (-hw - ro.x) / rd.x; if (tmx > 0.0 && tmx < surf.t) { vec3 p = ro + tmx * rd; if (p.y < 0.0 && abs(p.z) < hw) { hit = true; surf.t = tmx; surf.pos = p; surf.nor = vec3(-1.0, 0.0, 0.0); } } float tpz = (hw - ro.z) / rd.z; if (tpz > 0.0 && tpz < surf.t) { vec3 p = ro + tpz * rd; if (p.y < 0.0 && abs(p.x) < hw) { hit = true; surf.t = tpz; surf.pos = p; surf.nor = vec3(0.0, 0.0, 1.0); } } float tmz = (-hw - ro.z) / rd.z; if (tmz > 0.0 && tmz < surf.t) { vec3 p = ro + tmz * rd; if (p.y < 0.0 && abs(p.x) < hw) { hit = true; surf.t = tmz; surf.pos = p; surf.nor = vec3(0.0, 0.0, -1.0); } } if (hit) { surf.diffColor = vec3(0.5); surf.specColor = vec3(0.1); surf.diff = 0.8; surf.spec = 1.0; } } #define MAX_DISTANCE 1e8 const vec3 LIGHT_UP = normalize(vec3(0.07, 1.0, 0.1)); bool hitObjects(vec3 ro, vec3 rd, inout Surface surf) { surf.t = MAX_DISTANCE; for (int i = 0; i < SPHERE_NUM; i++) { if (hitSphere(ro, rd, SPHERE_RADIUSES[i], SPHERE_POSITIONS[i], surf)) { surf.diffColor = vec3(0.5); surf.specColor = vec3(0.02); surf.diff = 1.0; surf.spec = 1.0; } } hitGround(ro, rd, GROUND_WIDTH, surf); return surf.t != MAX_DISTANCE; } vec3 fresnelSchlick(vec3 f0, float cosine) { return f0 + (1.0 - f0) * pow(1.0 - cosine, 5.0); } vec3 background(vec3 rd) { return mix(vec3(0.0, 0.0, 0.0), vec3(1.0, 0.15, 0.0), rd.y * 0.5 + 0.5); } vec3 getColor(vec3 ro, vec3 rd) { vec3 color = vec3(0.0); vec3 scale = vec3(1.0); Surface surf; for (int i = 0; i < 3; i++) { if (!hitObjects(ro, rd, surf)) { color += scale * background(rd); break; } else { vec3 diff = surf.diff * surf.diffColor * (dot(surf.nor, LIGHT_UP) * 0.5 + 0.5); float ao = ambientOcclusion(surf.pos, surf.nor, 0.1); color += scale * ao * diff; } if (surf.spec == 0.0) { break; } vec3 refDir = reflect(rd, surf.nor); float dotNR = clamp(dot(surf.nor, refDir), 0.0, 1.0); vec3 fresnel = fresnelSchlick(surf.specColor, dotNR); scale *= surf.spec * fresnel; ro = surf.pos + 0.01 * refDir; rd = refDir; } return color; } void main(void) { initConstants(); vec2 st = (2.0 * gl_FragCoord.xy - resolution) / min(resolution.x, resolution.y); vec3 ro = vec3( 20.0 * cos(-0.5 * time), 5.0, 8.0 * sin(-0.5 * time) ); vec3 ta = vec3(0.0, 1.5, 0.0); vec3 z = normalize(ta - ro); vec3 up = vec3(0.0, 1.0, 0.0); vec3 x = normalize(cross(z, up)); vec3 y = normalize(cross(x, z)); vec3 rd = normalize(x * st.x + y * st.y + z * 1.5); vec3 c = getColor(ro, rd); gl_FragColor = vec4(pow(c, vec3(1.0 / 2.2)), 1.0); }

Pesudo Global Illumination