Overdid the raymarch experiment

3 files changed, 182 insertions, 38 deletions

diff --git a/src/main/resources/shaders/modules/sdf.cs b/src/main/resources/shaders/modules/sdf.cs
new file mode 100644
index 0000000..8121b18
--- /dev/null
+++ b/src/main/resources/shaders/modules/sdf.cs
@@ -0,0 +1,12 @@
+float sdf_circle(in vec3 p, in float radius) {
+  return length(p) - radius;
+}
+
+float sdf_plane(in vec3 p, in vec3 normal, in float offset) {
+  return dot(p, normal) + offset;
+}
+
+float sdf_box(in vec3 p, in vec3 dimens, in float rounding) {
+  vec3 q = abs(p) - dimens + rounding;
+  return length(max(q, 0.0)) + min(max(q.x, max(q.y, q.z)), 0.0) - rounding;
+}
diff --git a/src/main/resources/shaders/modules/utils.cs b/src/main/resources/shaders/modules/utils.cs
new file mode 100644
index 0000000..1616e8c
--- /dev/null
+++ b/src/main/resources/shaders/modules/utils.cs
@@ -0,0 +1,4 @@
+float smin(float a, float b, float k) {
+  float h = clamp(0.5 + 0.5 * (b - a) / k, 0.0, 1.0);
+  return mix(b, a, h) - k * h * (1.0 - h);
+}
diff --git a/src/main/resources/shaders/play_shader.cs b/src/main/resources/shaders/play_shader.cs
index d3cd4f5..c92e8b6 100644
--- a/src/main/resources/shaders/play_shader.cs
+++ b/src/main/resources/shaders/play_shader.cs
@@ -1,75 +1,203 @@
 #version 430
 layout(local_size_x = 1, local_size_y = 1) in;
 
+#include <sdf>
+#include <utils>
+
 uniform float seconds = 0;
-layout(rgba8) uniform writeonly image2D outputImg;
+layout(rgba8) uniform readonly image2D noise_texture;
+layout(rgba8) uniform writeonly image2D output_image;
+uniform vec3 camera_position = vec3(0, 1, 0);
+uniform vec3 uv_direction = vec3(0);
+uniform vec3 primary_light_position = vec3(1, 2, 1);
 
-#define MAX_ITERATIONS 500
+#define MAX_RAYMARCH_ITERATIONS 500
 #define MAX_DISTANCE 100.0
-#define SURF_DIST 0.01
+#define SURFACE_DIST 0.01
+
+// Noise Related Functions
+float mod289(float x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
+vec4 mod289(vec4 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
+vec4 perm(vec4 x) { return mod289(((x * 34.0) + 1.0) * x); }
+float noise(vec3 p) {
+  vec3 a = floor(p);
+  vec3 d = p - a;
+  d = d * d * (3.0 - 2.0 * d);
+  vec4 b = a.xxyy + vec4(0.0, 1.0, 0.0, 1.0);
+  vec4 k1 = perm(b.xyxy);
+  vec4 k2 = perm(k1.xyxy + b.zzww);
+  vec4 c = k2 + a.zzzz;
+  vec4 k3 = perm(c);
+  vec4 k4 = perm(c + 1.0);
+  vec4 o1 = fract(k3 * (1.0 / 41.0));
+  vec4 o2 = fract(k4 * (1.0 / 41.0));
+  vec4 o3 = o2 * d.z + o1 * (1.0 - d.z);
+  vec2 o4 = o3.yw * d.x + o3.xz * (1.0 - d.x);
+  return o4.y * d.y + o4.x * (1.0 - d.y);
+}
+float PHI = 1.61803398874989484820459; // Φ = Golden Ratio
+float gold_noise(in vec2 xy, in float seed) {
+  return fract(tan(distance(xy * PHI, xy) * seed) * xy.x);
+}
+float random(vec3 scale, float seed) {
+  return fract(sin(dot(gl_GlobalInvocationID.xyz + seed, scale)) * 43758.5453 +
+               seed);
+}
 
-float sdfCircle(in vec3 p, in vec3 origin, in float radius) {
-  return length(p - origin) - radius;
+// Fractal Brownian Noise
+float fbm(vec3 x, int octaves) {
+  float v = 0.0;
+  float a = 0.5;
+  vec3 shift = vec3(100);
+  for (int i = 0; i < octaves; ++i) {
+    v += a * noise(x);
+    x = x * 2.0 + shift;
+    a *= 0.5;
+  }
+  return v;
 }
 
-float smin(float a, float b, float k) {
-  float h = clamp(0.5 + 0.5 * (b - a) / k, 0.0, 1.0);
-  return mix(b, a, h) - k * h * (1.0 - h);
+float random(vec2 st) {
+  return fract(sin(dot(st.xy, vec2(12.9898, 78.233))) * 43758.5453123);
 }
 
-float scene(in vec3 p) {
-  float c1 = sdfCircle(p, vec3(0, 1, 2.4), 0.2);
-  float c2 = sdfCircle(p, vec3(-0.6, 1, 3), 0.3);
-  return min(c1, c2);
+float noise(vec2 st) {
+  vec2 i = floor(st);
+  vec2 f = fract(st);
+  float a = random(i);
+  float b = random(i + vec2(1.0, 0.0));
+  float c = random(i + vec2(0.0, 1.0));
+  float d = random(i + vec2(1.0, 1.0));
+  vec2 u = f * f * (3.0 - 2.0 * f);
+  return mix(a, b, u.x) + (c - a) * u.y * (1.0 - u.x) + (d - b) * u.x * u.y;
 }
 
-float ray_march_scene(in vec3 ray_origin, in vec3 ray_direction) {
+float fbm(vec2 st) {
+  float value = 0.0;
+  float amplitude = 0.5;
+  for (int i = 0; i < 5; i++) {
+    value += amplitude * noise(st);
+    st *= 2.0;
+    amplitude *= 0.5;
+  }
+  return value;
+}
+
+// TODO: Enumify
+#define OID_TERRAIN 4.
+
+vec2 scene(in vec3 p) {
+  float c1 = sdf_circle(p - vec3(0, 1, 2.4), 0.2);
+  float c2 = sdf_circle(p - vec3(-0.6, 1, 3), 0.3);
+  float box = sdf_box(p - vec3(1, 0.5, 3), vec3(0.5, 0.18, 0.2), 0.07);
+  float terrain_noise =
+      3.0 * noise(p / 20.0) + noise(p / 4.0) + noise(p * 5) / 30.0;
+  float terrain =
+      sdf_plane(p + vec3(0.0, terrain_noise, 0.0), vec3(0.0, 1.0, 0.0), 0.0);
+  float light_indicator =
+      sdf_circle(p - primary_light_position + vec3(0.1, 0.1, -0.4), 0.01);
+  float dist = min(min(min(min(c1, c2), terrain), box), light_indicator);
+  float oid = 0.;
+  if (dist == c1)
+    oid = 1.;
+  else if (dist == c2)
+    oid = 2.;
+  else if (dist == box)
+    oid = 3.;
+  else if (dist == terrain)
+    oid = OID_TERRAIN;
+  else if (dist == light_indicator)
+    oid = -1.;
+  return vec2(dist, oid);
+}
+
+vec2 ray_march_scene(in vec3 ray_origin, in vec3 ray_direction) {
   float dist = 0.;
-  for (int i = 0; i < MAX_ITERATIONS && dist < MAX_DISTANCE; i++) {
+  for (int i = 0; i < MAX_RAYMARCH_ITERATIONS && dist < MAX_DISTANCE; i++) {
     vec3 p = ray_origin + dist * ray_direction;
-    float gap = scene(p);
+    vec2 obj = scene(p);
+    float gap = obj.x;
     dist += gap;
-    if (gap <= SURF_DIST)
-      return dist;
+    if (gap <= SURFACE_DIST)
+      return vec2(dist, obj.y);
   }
-  return dist;
+  return vec2(dist, 0.0);
 }
 
 vec3 surface_normal_scene(in vec3 p) {
   vec2 inc = vec2(0.01, 0);
-  return normalize(vec3(scene(p + inc.xyy) - scene(p - inc.xyy),
-                        scene(p + inc.yxy) - scene(p - inc.yxy),
-                        scene(p + inc.yyx) - scene(p - inc.yyx)));
+  return normalize(vec3(scene(p + inc.xyy).x - scene(p - inc.xyy).x,
+                        scene(p + inc.yxy).x - scene(p - inc.yxy).x,
+                        scene(p + inc.yyx).x - scene(p - inc.yyx).x));
+}
+
+float shadow_scene(in vec3 ray_origin, in vec3 ray_direction,
+                   in float light_intensity) {
+  float dist = 0.;
+  float res = 1.;
+  float ph = 1e10;
+  for (int i = 0; i < 50 && dist < MAX_DISTANCE; i++) {
+    vec3 p = ray_origin + dist * ray_direction;
+    vec2 obj = scene(p);
+    float gap = obj.x;
+    if (obj.y < 0.) // Debug objects dont cast shadows
+      continue;
+    float y = gap * gap / (2.0 * ph);
+    float d = sqrt(gap * gap - y * y);
+    res = min(res, light_intensity * d / max(0.0, dist - y));
+    ph = gap;
+    dist += gap;
+
+    if (res < 0.0001)
+      break;
+  }
+  res = clamp(res, 0.08, 1.0);
+
+  return res * res * (3.0 - 2.0 * res);
 }
 
 void main() {
-  vec2 resolution = vec2(imageSize(outputImg).xy);
+  vec2 resolution = vec2(imageSize(output_image).xy);
   vec3 uv = vec3((gl_GlobalInvocationID.xy - resolution / 2.0) / resolution, 0);
   float aspect_ratio = resolution.y / resolution.x;
   uv /= vec3(aspect_ratio, 1, 1);
 
-  vec3 camera_pos = vec3(0, 1, 0);
-  vec3 camera_direction = normalize(vec3(uv.x, uv.y, 1.));
+  vec3 uv_direction = normalize(vec3(uv.x, uv.y, 1));
 
-  vec3 light_pos = vec3(1, 2. * sin(seconds), 1);
+  vec3 light_pos = primary_light_position;
 
-  float depth = ray_march_scene(camera_pos, camera_direction);
-  vec3 p = camera_pos + camera_direction * depth;
+  vec2 obj = ray_march_scene(camera_position, uv_direction);
+  float depth = obj.x;
+  float oid = obj.y;
+  vec3 p = camera_position + uv_direction * depth;
   vec3 normal = surface_normal_scene(p);
-  vec3 light_vec = normalize(light_pos - p);
+  vec3 light_dir = normalize(light_pos - p);
+  vec3 hal = normalize(light_dir - uv_direction);
 
-  float contrast = dot(normal, light_vec);
-  contrast = clamp(contrast, 0.1, 1.);
+  vec3 col = vec3(0.9, 0.3, 0.4);
+  if (oid < 0.) // Debug objects
+    col = vec3(1.0, 0.2, 0.2);
+  else if (oid == OID_TERRAIN)
+    col = vec3(0.24, 0.61, 0.08);
+  else if (oid == 0) { // Sky
+    vec4 cloud_noise =
+        imageLoad(noise_texture, ivec2(gl_GlobalInvocationID.xy));
+    col = vec3(0.35, 0.6, 0.9);
+    col = mix(col, cloud_noise.xyz, clamp(0.5, 0., 1.));
+  }
 
-  vec3 col = vec3(0.15);
-  if (depth < MAX_DISTANCE) {
-    float light_ray_dist =
-        ray_march_scene(p + 10. * normal * SURF_DIST, light_vec);
-    if (light_ray_dist < length(light_pos - p))
-      contrast *= 0.3;
-    col = vec3(0, 1. - (depth / MAX_DISTANCE), 0.4);
+  if (depth < MAX_DISTANCE && oid > 0.) {
+    float illumination = shadow_scene(p, light_dir, 24.0);
+    float contrast = clamp(dot(normal, light_dir), 0, 1.) * illumination;
+    float spe =
+        pow(clamp(dot(normal, hal), 0.0, 1.0), 16.0) * contrast *
+        (0.04 + 0.96 * pow(clamp(1.0 + dot(hal, uv_direction), 0.0, 1.0), 5.0));
+    col = col * 1.1 + 0.01;
+    col += 12.0 * spe * vec3(1.00, 0.70, 0.5);
     col *= contrast;
+    // col *= max(0.2, exp(-0.00005 * depth * depth * depth));
   }
 
-  imageStore(outputImg, ivec2(gl_GlobalInvocationID.xy), vec4(col, 1.));
+  imageStore(output_image, ivec2(gl_GlobalInvocationID.xy),
+             vec4(clamp(col, 0., 1.), 1));
 }