displacement mapping

tinykaboom.cpp

@@ -8,9 +8,12 @@
 #include "geometry.h"
 
 const float sphere_radius   = 1.5;
+const float noise_amplitude = 0.2;
 
 float signed_distance(const Vec3f &p) {
-    return p.norm() - sphere_radius;
+    Vec3f s = Vec3f(p).normalize(sphere_radius);
+    float displacement = sin(16*s.x)*sin(16*s.y)*sin(16*s.z)*noise_amplitude;
+    return p.norm() - (sphere_radius + displacement);
 }
 
 bool sphere_trace(const Vec3f &orig, const Vec3f &dir, Vec3f &pos) {
@@ -48,8 +51,7 @@ int main() {
             if (sphere_trace(Vec3f(0, 0, 3), Vec3f(dir_x, dir_y, dir_z).normalize(), hit)) { // the camera is placed to (0,0,3) and it looks along the -z axis
                 Vec3f light_dir = (Vec3f(10, 10, 10) - hit).normalize();                     // one light is placed to (10,10,10)
                 float light_intensity  = std::max(0.4f, light_dir*distance_field_normal(hit));
-                float displacement = (sin(16*hit.x)*sin(16*hit.y)*sin(16*hit.z) + 1.)/2.;
-                framebuffer[i+j*width] = Vec3f(1, 1, 1)*displacement*light_intensity;
+                framebuffer[i+j*width] = Vec3f(1, 1, 1)*light_intensity;
             } else {
                 framebuffer[i+j*width] = Vec3f(0.2, 0.7, 0.8); // background color
             }