114 lines
2.4 KiB
GLSL
114 lines
2.4 KiB
GLSL
#version 460 core
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in vec2 pos;
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out vec4 color;
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layout(location = 0) uniform float aspect_ratio;
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layout(location = 1) uniform float sphere_y;
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layout(std430, binding = 0) buffer data
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{
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int ray_count;
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};
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struct Ray {
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vec3 origin;
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vec3 direction;
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};
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struct Sphere {
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vec3 center;
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float radius;
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};
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vec3 unit_vector(vec3 v) {
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return v / length(v);
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}
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float length_squared(vec3 v) {
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float length = length(v);
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return length * length;
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}
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float hit_sphere(Ray r, Sphere s) {
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vec3 oc = s.center - r.origin;
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float a = length_squared(r.direction);
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float h = dot(r.direction, oc);
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float c = length_squared(oc) - s.radius * s.radius;
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float discriminant = h * h - a * c;
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if(discriminant > 0.0) {
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return (h - sqrt(discriminant)) / a;
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}
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return -1.0;
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}
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vec3 at(Ray r, float time) {
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return r.origin + time * r.direction;
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}
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vec3 get_normal_color(Ray r, vec3 pos, Sphere s) {
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vec3 normal = unit_vector(pos - s.center);
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return 0.5 * vec3(normal + vec3(1.0, 1.0, 1.0));
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}
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Sphere spheres[] = {
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Sphere(vec3(0, sphere_y, -1), 0.5),
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Sphere(vec3(2, 0, 0), 0.25),
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Sphere(vec3(0, -100.5, -1), 100.0)
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};
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struct HitInfo {
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vec3 pos;
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bool hit;
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int index;
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};
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HitInfo hit_spheres(Ray r) {
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float t_min = 0;
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int index;
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bool hit = false;
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for(int i = 0; i < spheres.length(); i++) {
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Sphere s = spheres[i];
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float t = hit_sphere(r, s);
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if(t > 0.0 && (!hit || t < t_min)) {
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t_min = t;
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index = i;
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hit = true;
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}
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}
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return HitInfo(hit ? at(r, t_min) : vec3(0.0), hit, index);
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}
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vec3 ray_color(Ray r) {
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HitInfo info = hit_spheres(r);
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if(info.hit) {
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vec3 sun_dir = vec3(10, 10, 10) - info.pos;
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Ray sun_ray = Ray(info.pos, sun_dir);
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HitInfo sun_hit = hit_spheres(sun_ray);
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return get_normal_color(r, info.pos,
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spheres[info.index]) -
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(sun_hit.hit && sun_hit.index != info.index ? 0.4 : 0.0);
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}
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vec3 unit_direction = unit_vector(r.direction);
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float a = 0.5 * (unit_direction.y + 1.0);
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return (1.0 - a) * vec3(1.0, 1.0, 1.0) + a * vec3(0.5, 0.7, 1.0);
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}
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void main() {
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vec3 p = vec3(pos, 0.0);
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p.x *= aspect_ratio;
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vec3 camera_pos = vec3(0.0, 0.0, 0.0);
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camera_pos.z += 1.0;
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vec3 ray_dir = p - camera_pos;
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Ray r = Ray(camera_pos, ray_dir);
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color = vec4(ray_color(r), 1.0);
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}
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