1 files changed, 72 insertions, 5 deletions
diff --git a/resources/shaders/main.glsl b/resources/shaders/main.glsl
index 7d4067a..2888d56 100644
--- a/resources/shaders/main.glsl
+++ b/resources/shaders/main.glsl
@@ -18,9 +18,76 @@ uniform float time;
 
 out vec3 color;
 
-void main(){
-	vec2 coord=gl_FragCoord.xy/resolution;
-	coord-=0.5;
-	float d=length(coord);
-	color=vec3(d,1,1);
+
+#define MAX_STEPS 100
+#define MAX_DIST 100.
+#define SURF_DIST .01
+
+float GetDist(vec3 p) {
+	vec4 s = vec4(0, 1, 6, 1);
+    
+    float sphereDist =  length(p-s.xyz)-s.w;
+    float planeDist = p.y;
+    
+    float d = min(sphereDist, planeDist);
+    return d;
+}
+
+float RayMarch(vec3 ro, vec3 rd) {
+	float dO=0.;
+    
+    for(int i=0; i<MAX_STEPS; i++) {
+    	vec3 p = ro + rd*dO;
+        float dS = GetDist(p);
+        dO += dS;
+        if(dO>MAX_DIST || dS<SURF_DIST) break;
+    }
+    
+    return dO;
+}
+
+vec3 GetNormal(vec3 p) {
+	float d = GetDist(p);
+    vec2 e = vec2(.01, 0);
+    
+    vec3 n = d - vec3(
+        GetDist(p-e.xyy),
+        GetDist(p-e.yxy),
+        GetDist(p-e.yyx));
+    
+    return normalize(n);
+}
+
+float GetLight(vec3 p) {
+    vec3 lightPos = vec3(0, 5, 6);
+    lightPos.xz += vec2(sin(time), cos(time))*2.;
+    vec3 l = normalize(lightPos-p);
+    vec3 n = GetNormal(p);
+    
+    float dif = clamp(dot(n, l), 0., 1.);
+    float d = RayMarch(p+n*SURF_DIST*2., l);
+    if(d<length(lightPos-p)) dif *= .1;
+    
+    return dif;
+}
+
+void main()
+{
+    vec2 uv = (gl_FragCoord.xy-.5*resolution.xy)/resolution.y;
+
+    vec3 col = vec3(0);
+    
+    vec3 ro = vec3(0, 1, 0);
+    vec3 rd = normalize(vec3(uv.x, uv.y, 1));
+
+    float d = RayMarch(ro, rd);
+    
+    vec3 p = ro + rd * d;
+    
+    float dif = GetLight(p);
+    col = vec3(dif);
+    
+    col = pow(col, vec3(.4545));	// gamma correction
+    
+    color = col;
 }