1 files changed, 185 insertions, 0 deletions
diff --git a/src/shader.frag b/src/shader.frag
new file mode 100644
index 0000000..b4cabf9
--- /dev/null
+++ b/src/shader.frag
@@ -0,0 +1,185 @@
+#version 410 core
+
+uniform vec2 u_resolution; // viewport resolution (in pixels)
+uniform float u_time; // in seconds
+uniform float u_xrot;
+uniform float u_yrot;
+uniform float u_zrot;
+uniform sampler1D texFFT;
+
+layout(location = 0) out vec4 out_color; // out_color must be written in order to see anything
+
+const int   MAX_STEP = 255;
+const float MIN_DIST = 0.0;
+const float MAX_DIST = 100.0;
+const float EPSILON  = 0.0001;
+
+float f(float x, float z)
+{
+  return 2.0;
+}
+
+
+// transformations
+mat4 rotateX(float theta)
+{
+  float c = cos(theta);
+  float s = sin(theta);
+
+  return mat4(
+    vec4(1, 0, 0, 0),
+    vec4(0, c, s, 0),
+    vec4(0, -s, c, 0),
+    vec4(0, 0, 0, 1)
+  );  
+}
+
+// transformations
+mat4 rotateY(float theta)
+{
+  float c = cos(theta);
+  float s = sin(theta);
+
+  return mat4(
+    vec4(c, 0, s, 0),
+    vec4(0, 1, 0, 0),
+    vec4(-s, 0, c, 0),
+    vec4(0, 0, 0, 1)
+  );  
+}
+
+// transformations
+mat4 rotateZ(float theta)
+{
+  float c = cos(theta);
+  float s = sin(theta);
+
+  return mat4(
+    vec4(c, s, 0, 0),
+    vec4(-s, c, 0, 0),
+    vec4(0, 0, 1, 0),
+    vec4(0, 0, 0, 1)
+  );  
+}
+
+float tHeight(vec2 p)
+{
+  return smoothstep(0.0, 200.0, p.y*20000)*5;
+}
+
+float torusSDF( vec3 p, vec2 t )
+{
+  vec2 q = vec2(length(p.xz)-t.x,p.y);
+  float d1 = length(p)-0.4;
+  float d2 = tHeight(p.xy)*0.45;
+  return d1 + (d2/20);
+}
+
+vec3 transformScene(vec3 p)
+{
+    //p = (inverse(rotateX(u_time*3)) * vec4(p, 1.0)).xyz;
+    p = (inverse(rotateX(u_xrot)) *
+         inverse(rotateY(u_yrot)) *
+         inverse(rotateZ(u_zrot)) * vec4(p, 1.0)).xyz;
+    return p;
+}
+
+// Standard distance function for the whole scene!
+float sceneSDF(vec3 p)
+{
+  p = transformScene(p);
+  //p = p * vec3(1.0, sin(u_time),1.0);
+  return torusSDF(p, vec2(0.3, 0.1));
+}
+
+vec3 estNormal(vec3 p)
+{
+  return normalize(vec3(
+    sceneSDF(vec3(p.x + EPSILON, p.y, p.z)) - sceneSDF(vec3(p.x - EPSILON, p.y, p.z)),
+    sceneSDF(vec3(p.x, p.y + EPSILON, p.z)) - sceneSDF(vec3(p.x, p.y - EPSILON, p.z)),
+    sceneSDF(vec3(p.x, p.y, p.z + EPSILON)) - sceneSDF(vec3(p.x, p.y, p.z - EPSILON))
+  ));
+}
+
+vec3 rayDirection(float fov, vec2 size, vec2 fragCoord)
+{
+  vec2 xy = fragCoord - size / 2.0;
+  float z = size.y  / tan(radians(fov) / 2.0);
+  return normalize(vec3(xy, -z));
+}
+
+// Raymarcher!
+float march(vec3 eye, vec3 dir, float start, float end)
+{
+  float depth = start;
+  for (int i=0; i<MAX_STEP; i++) {
+    float dist = sceneSDF(eye + depth * dir);
+    if (dist < 0.0001) {
+      return depth; // we're inside the scene
+    }
+    depth+=dist;
+    if (depth >= end) {
+      return end; // gone too far! 
+    }
+  }
+}
+
+// Does something related to phong for each light that we want
+vec3 phongLightContrib(vec3 kd, vec3 ks, float alpha, vec3 p, vec3 eye, vec3 lightPos, vec3 lightInt)
+{
+  vec3 N = estNormal(p);
+  vec3 L = normalize(lightPos - p);
+  vec3 V = normalize(eye - p);
+  vec3 R = normalize(reflect(-L, N));
+
+  float dotLN = dot(L, N);
+  float dotRV = dot(R, V);
+
+  if (dotLN < 0.0) {return vec3(0.0);}
+  if (dotRV < 0.0) {return lightInt * (kd * dotLN);}
+  return lightInt * (kd * dotLN + ks * pow(dotRV, alpha));
+}
+
+vec3 phong(vec3 ka, vec3 kd, vec3 ks, float alpha, vec3 p, vec3 eye)
+{
+  const vec3 ambientLux = vec3(0.3);
+  vec3 colour = ambientLux * ka;
+  
+  vec3 light1Pos = vec3(-1.0, -1.2, 0.7);
+  vec3 light1Int = vec3(0.2);
+  
+  vec3 light2Pos = vec3(0.8, 0.8, 1.2);
+  vec3 light2Int = vec3(0.55);
+  
+  colour += phongLightContrib(kd, ks, alpha, p, eye, light1Pos, light1Int);
+  colour += phongLightContrib(kd, ks, alpha, p, eye, light2Pos, light2Int);
+  return colour;
+}
+
+void main(void)
+{
+  vec3 dir = rayDirection(45.0, u_resolution.xy, gl_FragCoord.xy);
+  vec3 eye = vec3(0.0,0.0,5.0);
+  float dist = march(eye, dir, MIN_DIST, MAX_DIST);
+  
+  if (dist > MAX_DIST - EPSILON) {out_color = vec4(0.1); return;}
+  
+  vec3 p = eye + dist * dir;
+  vec3 colour;
+  
+  vec3 Ka = vec3(0.0, 0.729, 0.745)*texture(texFFT, 0.123).r*1000; // ambient  reflection constant
+  vec3 Kd = vec3(0.0, 0.467, 0.745);                               // diffuse  reflection constant
+  vec3 Ks = vec3(0.0, 0.0, 0.0);                                   // specular reflection constant
+  float shininess = 1.0;
+  colour = phong(Ka, Kd, Ks, shininess, p, eye);
+  
+  if (transformScene(p).y< 0) {
+    vec3 Ka = vec3(0.2);            // ambient  reflection constant
+    vec3 Kd = vec3(0.95, 0.2, 0.1); // diffuse  reflection constant
+    vec3 Ks = vec3(0.95, 0.2, 0.1); // specular reflection constant
+    float shininess = 300.0;
+    colour = phong(Ka, Kd, Ks, shininess, p, eye);
+  }
+  
+  out_color = vec4(colour, 1.0);
+}