From 428b43168541e68f3fef76daa90153ee2e126c9a Mon Sep 17 00:00:00 2001 From: John Tsiombikas Date: Mon, 7 Dec 2020 23:33:17 +0200 Subject: [PATCH] whitted: recursion emulation --- sdr/whitted.p.glsl | 155 ++++++++++++++++++++++++++++++++++++++++++++-------- sdr/whitted.v.glsl | 2 +- 2 files changed, 134 insertions(+), 23 deletions(-) diff --git a/sdr/whitted.p.glsl b/sdr/whitted.p.glsl index 0124f1b..055a818 100644 --- a/sdr/whitted.p.glsl +++ b/sdr/whitted.p.glsl @@ -1,6 +1,13 @@ +struct Ray { + vec3 org, dir; + float energy, ior; +}; + struct Material { vec3 diffuse, specular; float shin; + float refl, refr; + float ior; }; struct HitPoint { @@ -8,6 +15,7 @@ struct HitPoint { vec3 pos, norm; vec2 surfpos; Material mtl; + float shadow; /* opacity along the line of sight up to dist=1 */ }; varying vec3 v_rorg, v_rdir; @@ -24,43 +32,121 @@ bool isect_sphere(in vec3 ro, in vec3 rd, in vec3 pos, float rad, out HitPoint h vec3 tex_chess(in vec3 col1, in vec3 col2, in vec2 spos); -const Material mtl_sph = Material(vec3(1.0, 0.0, 0.0), vec3(1.0, 1.0, 1.0), 80.0); -const Material mtl_floor = Material(vec3(0.5, 0.5, 0.5), vec3(0.0, 0.0, 0.0), 1.0); +const Material mtl_sph = Material(vec3(1.0, 1.0, 1.0) * 0.1, vec3(1.0, 1.0, 1.0), 80.0, 0.8, 0.0, 1.0); +const Material mtl_glass = Material(vec3(1.0, 1.0, 1.0) * 0.01, vec3(1.0, 1.0, 1.0), 80.0, 0.0, 0.99, 1.52); +const Material mtl_air = Material(vec3(1.0, 1.0, 1.0) * 0.01, vec3(1.0, 1.0, 1.0), 80.0, 0.0, 0.99, 1.0); +const Material mtl_floor = Material(vec3(0.5, 0.5, 0.5), vec3(0.0, 0.0, 0.0), 1.0, 0.0, 0.0, 1.0); const vec3 light_pos = vec3(-10, 50, 30); -void main() +bool cast_ray(in Ray ray, inout vec3 color, out HitPoint hit) { - vec3 rdir = normalize(v_rdir); - gl_FragColor.rgb = backdrop(rdir); + if(isect_scene(ray.org, ray.dir, hit)) { + color += shade(ray.org, ray.dir, hit) * ray.energy; + return true; + } + color += backdrop(ray.dir); + return false; +} +#define MAX_LEVEL 8 + +struct StackFrame { + int op; + Ray ray; HitPoint hit; - if(isect_scene(v_rorg, rdir, hit)) { - gl_FragColor.rgb = shade(v_rorg, rdir, hit); - } else { - gl_FragColor.rgb = backdrop(rdir); +}; + +void main() +{ + StackFrame stack[MAX_LEVEL]; + + vec3 color = vec3(0.0, 0.0, 0.0); + + stack[0].op = 0; + stack[0].ray.org = v_rorg; + stack[0].ray.dir = normalize(v_rdir); + stack[0].ray.energy = stack[0].ray.ior = 1.0; + + int top = 0; + while(top >= 0) { + if(top >= MAX_LEVEL - 1) { + color += backdrop(stack[top].ray.dir) * stack[top].ray.energy; + top--; + continue; + } + if(stack[top].ray.energy < 1e-3) { + top--; + continue; + } + + if(!cast_ray(stack[top].ray, color, stack[top].hit)) { + /* no hit, return */ + top--; + continue; + } + + /* found a hit, recurse for reflection/refraction */ + HitPoint hit = stack[top].hit; + + // 1.0 when entering, 0.0 when leaving + float entering = step(0.0, dot(-stack[top].ray.dir, hit.norm)); + vec3 norm = faceforward(hit.norm, stack[top].ray.dir, hit.norm); + + int op = stack[top].op++; + if(op == 0) { + // reflection + float energy = stack[top].ray.energy * hit.mtl.refl; + if(energy > 1e-4) { + int next = top + 1; + stack[next].op = 0; + stack[next].ray.org = hit.pos + norm * 1e-5; + stack[next].ray.dir = reflect(stack[top].ray.dir, norm); + stack[next].ray.energy = energy; + top = next; + } + } else if(op == 1) { + // refraction + float energy = stack[top].ray.energy * hit.mtl.refr; + if(energy > 1e-4) { + float next_ior = mix(stack[top - 1].ray.ior, hit.mtl.ior, entering); + float ior = stack[top].ray.ior / next_ior; + int next = top + 1; + stack[next].op = 0; + stack[next].ray.org = hit.pos - norm * 1e-5; + stack[next].ray.dir = refract(stack[top].ray.dir, norm, ior); + stack[next].ray.energy = energy; + stack[next].ray.ior = next_ior; + top = next; + } + } else if(op == 2) { + // return + top--; + } } - gl_FragColor.a = 1.0; + + gl_FragColor = vec4(color, 1.0); } vec3 shade(in vec3 ro, in vec3 rd, in HitPoint hit) { HitPoint shadow_hit; + vec3 norm = faceforward(hit.norm, rd, hit.norm); vec3 ldir = light_pos - hit.pos; - vec3 col = vec3(0.03, 0.03, 0.03); // ambient + vec3 amb = hit.mtl.diffuse * 0.02; - if(!isect_scene(hit.pos + hit.norm * 0.01, ldir, shadow_hit) || shadow_hit.dist > 1.0) { - vec3 l = normalize(ldir); - vec3 v = normalize(-rd); - vec3 h = normalize(v + l); - float ndotl = max(dot(hit.norm, l), 0.0); - float ndoth = max(dot(hit.norm, h), 0.0); + isect_scene(hit.pos + norm * 0.01, ldir, shadow_hit); - col += hit.mtl.diffuse * ndotl + hit.mtl.specular * pow(ndoth, hit.mtl.shin); - } + vec3 l = normalize(ldir); + vec3 v = normalize(-rd); + vec3 h = normalize(v + l); + float ndotl = max(dot(norm, l), 0.0); + float ndoth = max(dot(norm, h), 0.0); - return col; + vec3 lit = hit.mtl.diffuse * ndotl + hit.mtl.specular * pow(ndoth, hit.mtl.shin); + + return amb + lit * shadow_hit.shadow; } #define M_PI 3.1415926 @@ -68,21 +154,44 @@ vec3 shade(in vec3 ro, in vec3 rd, in HitPoint hit) vec3 backdrop(in vec3 dir) { - return mix(vec3(0.8, 0.3, 0.2), vec3(0.2, 0.3, 0.8), smoothstep(-0.1, 0.1, dir.y)); + return vec3(0.1, 0.15, 1.0); } #define FLOOR_OFFS vec3(3.0, 0.0, 0.0) #define FLOOR_SIZE vec2(5.5, 15.0) +#define GLASS_POS vec3(0.0, 0.2, 1.2) + bool isect_scene(in vec3 ro, in vec3 rd, out HitPoint hit_res) { + float opacity = 1.0; HitPoint hit, nearest; nearest.dist = 10000.0; - if(isect_sphere(ro, rd, vec3(1.0, 0.0, 0.0), 1.0, hit)) { + if(isect_sphere(ro, rd, vec3(1.5, -0.5, 0.0), 0.85, hit)) { nearest = hit; nearest.mtl = mtl_sph; + if(hit.dist < 1.0) { + opacity *= mtl_sph.refr; + } + } + + if(isect_sphere(ro, rd, GLASS_POS, 0.9, hit)) { + if(hit.dist < nearest.dist) { + nearest = hit; + nearest.mtl = mtl_glass; + } + if(hit.dist < 1.0) { + opacity *= mtl_glass.refr; + } + } + + if(isect_sphere(ro, rd, GLASS_POS, 0.86, hit)) { + if(hit.dist < nearest.dist) { + nearest = hit; + nearest.mtl = mtl_air; + } } if(isect_floor(ro, rd, FLOOR_SIZE, hit) && hit.dist < nearest.dist) { @@ -92,10 +201,12 @@ bool isect_scene(in vec3 ro, in vec3 rd, out HitPoint hit_res) } if(nearest.dist >= 10000.0) { + hit_res.shadow = 1.0; return false; } hit_res = nearest; + hit_res.shadow = opacity; return true; } diff --git a/sdr/whitted.v.glsl b/sdr/whitted.v.glsl index 5e0aff2..4e18772 100644 --- a/sdr/whitted.v.glsl +++ b/sdr/whitted.v.glsl @@ -1,4 +1,4 @@ -#define FOV 0.9 +#define FOV 0.8 uniform float aspect; -- 1.7.10.4