+struct Material {
+ vec3 diffuse, specular;
+ float shin;
+};
+
+struct HitPoint {
+ float dist;
+ vec3 pos, norm;
+ vec2 surfpos;
+ Material mtl;
+};
+
varying vec3 v_rorg, v_rdir;
-vec3 shade(in vec3 pos, in vec3 norm);
+
+vec3 shade(in vec3 ro, in vec3 rd, in HitPoint hit);
vec3 backdrop(in vec3 dir);
-float isect_plane(in vec3 ro, in vec3 rd, out vec3 norm_ret);
+
+bool isect_scene(in vec3 ro, in vec3 rd, out HitPoint hit);
+
+bool isect_floor(in vec3 ro, in vec3 rd, in vec2 sz, out HitPoint hit);
+bool isect_plane(in vec3 ro, in vec3 rd, in vec4 plane, out HitPoint hit);
+bool isect_sphere(in vec3 ro, in vec3 rd, in vec3 pos, float rad, out HitPoint hit);
+
+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 vec3 light_pos = vec3(-10, 50, 30);
void main()
{
vec3 rdir = normalize(v_rdir);
+ gl_FragColor.rgb = backdrop(rdir);
- float t = isect_floor(v_rorg, rdir);
- if(t >= 0.0) {
- gl_FragColor.rgb = shade(v_rorg + rdir * t, vec3(0.0, 1.0, 0.0));
+ HitPoint hit;
+ if(isect_scene(v_rorg, rdir, hit)) {
+ gl_FragColor.rgb = shade(v_rorg, rdir, hit);
} else {
gl_FragColor.rgb = backdrop(rdir);
}
gl_FragColor.a = 1.0;
}
-vec3 shade(in vec3 pos, in vec3 norm)
+vec3 shade(in vec3 ro, in vec3 rd, in HitPoint hit)
{
+ HitPoint shadow_hit;
+ vec3 ldir = light_pos - hit.pos;
+
+ vec3 col = vec3(0.03, 0.03, 0.03); // ambient
+
+ 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);
+
+ col += hit.mtl.diffuse * ndotl + hit.mtl.specular * pow(ndoth, hit.mtl.shin);
+ }
+
+ return col;
}
+#define M_PI 3.1415926
+#define M_2PI (M_PI * 2.0)
+
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));
+}
+
+#define FLOOR_OFFS vec3(3.0, 0.0, 0.0)
+#define FLOOR_SIZE vec2(5.5, 15.0)
+
+bool isect_scene(in vec3 ro, in vec3 rd, out HitPoint hit_res)
+{
+ HitPoint hit, nearest;
+
+ nearest.dist = 10000.0;
+
+ if(isect_sphere(ro, rd, vec3(1.0, 0.0, 0.0), 1.0, hit)) {
+ nearest = hit;
+ nearest.mtl = mtl_sph;
+ }
+
+ if(isect_floor(ro, rd, FLOOR_SIZE, hit) && hit.dist < nearest.dist) {
+ nearest = hit;
+ nearest.mtl = mtl_floor;
+ nearest.mtl.diffuse = tex_chess(vec3(1.0, 0.0, 0.0), vec3(1.0, 1.0, 0.0), hit.surfpos);
+ }
+
+ if(nearest.dist >= 10000.0) {
+ return false;
+ }
+
+ hit_res = nearest;
+ return true;
+}
+
+bool isect_floor(in vec3 ro, in vec3 rd, in vec2 sz, out HitPoint hit)
+{
+ if(!isect_plane(ro - FLOOR_OFFS, rd, vec4(0.0, 1.0, 0.0, -1.8), hit)) {
+ return false;
+ }
+
+ if(abs(hit.pos.x) >= sz.x || abs(hit.pos.z) >= sz.y) {
+ return false;
+ }
+
+ hit.pos += FLOOR_OFFS;
+ hit.surfpos /= sz * 2.0;
+ return true;
+}
+
+bool isect_plane(in vec3 ro, in vec3 rd, in vec4 plane, out HitPoint hit)
+{
+ float ndotrd = dot(rd, plane.xyz);
+
+ if(abs(ndotrd) < 1e-6) {
+ return false;
+ }
+
+ vec3 pp = plane.xyz * plane.w;
+ vec3 pdir = pp - ro;
+ float t = dot(pdir, plane.xyz) / ndotrd;
+
+ if(t < 1e-6) {
+ return false;
+ }
+
+ hit.dist = t;
+ hit.pos = ro + rd * t;
+ hit.norm = plane.xyz;
+ hit.surfpos = hit.pos.xz; /* XXX */
+ return true;
}
-float isect_floor(in vec3 ro, in vec3 rd)
+bool isect_sphere(in vec3 ro, in vec3 rd, in vec3 pos, float rad, out HitPoint hit)
{
- float t = isect_plane(ro, rd, vec4(0.0, 1.0, 0.0, -1.0));
- if(t < 0.0) return t;
+ float a = dot(rd, rd);
+ float b = dot(rd * 2.0, (ro - pos));
+ float c = dot(ro, ro) + dot(pos, pos) - 2.0 * dot(ro, pos) - rad * rad;
- vec3 p = ro + rd * t;
- float d = max(abs(p.x), max(abs(p.y), abs(p.z)));
- if(d >= 1.0) return -1.0;
+ float d = b * b - 4.0 * a * c;
+ if(d < 1e-6) {
+ return false;
+ }
+
+ float t0 = (-b + sqrt(d)) / (2.0 * a);
+ float t1 = (-b - sqrt(d)) / (2.0 * a);
+
+ if(t0 < 0.0) t0 = t1;
+ if(t1 < 0.0) t1 = t0;
+ float t = min(t0, t1);
- return t;
+ if(t < 1e-6) {
+ return false;
+ }
+
+ hit.dist = t;
+ hit.pos = ro + rd * t;
+ hit.norm = normalize(hit.pos - pos);
+ hit.surfpos.x = atan(hit.norm.z, hit.norm.x);
+ hit.surfpos.y = acos(hit.norm.y);
+ return true;
}
-float isect_plane(in vec3 ro, in vec3 rd, in vec4 plane)
+vec3 tex_chess(in vec3 col1, in vec3 col2, in vec2 spos)
{
+ float foo = step(0.5, mod(spos.x * 8.0, 1.0)) * 2.0 - 1.0;
+ float bar = step(0.5, mod(spos.y * 24.0, 1.0)) * 2.0 - 1.0;
+
+ float xor = (foo * bar) * 0.5 + 0.5;
+ return mix(col1, col2, xor);
}