basic phong illumination

shaders/shader.fs

@@ -1,7 +1,5 @@
 #version 330 core
 
-in vec2 fragcoord;
-
 uniform vec2 u_resolution;
 uniform float u_time;
 uniform float u_deltatime;
@@ -9,6 +7,9 @@ uniform vec3 u_camorigin;
 uniform vec3 u_camdir;
 uniform vec3 u_camup;
 
+out vec4 FragColor;
+
+// START OF SDFs
 float sdfSphere(in vec3 point, in vec3 center, float r)
 {
     return length(point - center) - r;
@@ -24,10 +25,10 @@ float opUnion( float d1, float d2 ) { return min(d1,d2); }
 float sdfScene(in vec3 p){
     return opUnion(opUnion( sdfSphere(p, vec3(0.0), 1), sdfBox(p, vec3(2.0, 0.0, 0.0), vec3(0.8))), sdfBox(p, vec3(-5.0, 0.0, 0.0), vec3(2.0, 1.0, 0.5)));
 }
-
+// END OF SDFs
 
 vec3 sceneNormal(in vec3 p){
-    vec3 smallstep = vec3(0.0001, 0.0, 0.0);
+    vec3 smallstep = vec3(0.00001, 0.0, 0.0);
 
     float gradient_x = sdfScene(p.xyz + smallstep.xyy) - sdfScene(p.xyz - smallstep.xyy);
     float gradient_y = sdfScene(p.xyz + smallstep.yxy) - sdfScene(p.xyz - smallstep.yxy);
@@ -36,23 +37,54 @@ vec3 sceneNormal(in vec3 p){
     return normalize(vec3(gradient_x, gradient_y, gradient_z));
 }
 
+// START OF LIGHTNING
+float ambientStrength = 0.15;
+float specularStrength = 0.5;
+vec3 lightColor = vec3(1.0);
+vec3 ambient = lightColor * ambientStrength;
+vec3 lightPos = vec3(5.0);
+vec3 lightDir;
+// END OF LIGHTNING
+
 vec3 ray_march(in vec3 ro, in vec3 rd)
 {
     float total_dist = 0.0;
     vec3 pos;
 
     for(int i = 0; i < 35; i++){
+        // incrementally travel following the ray
         pos = ro + rd * total_dist;
 
+        // calculate distance from scene
         float dist = sdfScene(pos);
-
+        
+        // if close to the scene, color the pixel as needed 
         if(dist <= 0.001){
-            return (sceneNormal(pos) * 0.5 + 0.5);
+            // Basic Phong illumination
+            // diffuse
+            lightDir = normalize(lightPos - pos);
+            float diff = max(dot(sceneNormal(pos), lightDir), 0.0);
+            vec3 diffuse = diff * lightColor;
+
+            // specular
+            vec3 viewDir = normalize(u_camorigin - pos);
+            vec3 reflectDir = reflect(-lightDir, sceneNormal(pos));
+
+            float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
+            vec3 specular = specularStrength * spec * lightColor;
+
+            return (ambient + diffuse + specular) * vec3(1.0, 0.0, 0.0);
         }
+
+        // increment distance by the highest possible value (sphere marching)
         total_dist += dist;
-        if(total_dist > 4000) break;
+
+        // if too far out, bail out
+        if(total_dist > 1000) break;
 
     }
+
+    // no hit, return background color
     return vec3(0.0);
 }
 
@@ -72,5 +104,5 @@ void main()
     vec3 rd = normalize(uv.x * camright + uv.y * camup + u_camdir * fPersp);
 
     vec3 shaded_color = ray_march(u_camorigin, rd);
-    gl_FragColor = vec4(shaded_color, 1.0);
+    FragColor = vec4(shaded_color, 1.0);
 }