reflection

1 files changed, 36 insertions, 8 deletions

diff --git a/src/main.c b/src/main.c
index e21ec2a..1cf1d5f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -34,6 +34,7 @@ typedef struct {
     float r;
     Color color;
     float specular;
+    float reflective;
 } Ball;
 
 Ball balls[] = {
@@ -41,21 +42,25 @@ Ball balls[] = {
         .center = {.x = 0, .y = -1, .z = 3},
         .r = 1,
         .specular = 500,
+        .reflective = 0.2,
     },
     {
         .center = {.x = 2, .y = 0, .z = 4},
         .r = 1,
         .specular = 500,
+        .reflective = 0.3,
     },
     {
         .center = {.x = -2, .y = 0, .z = 4},
         .r = 1,
         .specular = 10,
+        .reflective = 0.4,
     },
     {
         .center = {0, -5001, 0},
         .r = 5000,
         .specular = 1000,
+        .reflective = 0.5,
     },
 };
 
@@ -84,7 +89,7 @@ void init_color() {
     balls[1].color = icolor(0xfce38a);
     balls[2].color = icolor(0xf38181);
     balls[3].color = icolor(0xeaffd0);
-    gBackgroupColor = icolor(0xeaeaea);
+    // gBackgroupColor = icolor(0xeaeaea);
 }
 
 float ball_intersect(Vec3f start, Vec3f ray, Ball *ball) {
@@ -124,8 +129,13 @@ bool is_in_shadow(Vec3f pos, Light light) {
     return false;
 }
 
+Vec3f reflection(Vec3f rayin, Vec3f norm) {
+    rayin = vec3f_normalize(vec3f_neg(rayin));
+    return vec3f_sub(vec3f_mul(2 * vec3f_dot(norm, rayin), norm), rayin);
+}
+
 float specular_coeff(Vec3f l, Vec3f n, Vec3f v, float s) {
-    Vec3f r = vec3f_sub(vec3f_mul(2 * vec3f_dot(n, l), n), l);
+    Vec3f r = reflection(vec3f_neg(l), n);
     v = vec3f_normalize(v);
     float prod = vec3f_dot(r, vec3f_neg(v));
     if (prod < 0) return 0;
@@ -166,11 +176,13 @@ Color ball_surface_color(Ball *ball, Vec3f point, Vec3f view) {
     };
 }
 
-Color calc_color(Vec3f v) {
-    Vec3f start = {.x = 0, .y = 0, .z = 0};
-    float tmin = 0.1;
-    float tmax = FLT_MAX;
+#define MAX_TRACE_DEPTH 3
 
+Vec3f ball_norm(Vec3f center, Vec3f pos) {
+    return vec3f_normalize(vec3f_sub(pos, center));
+}
+
+Color calc_color(Vec3f start, Vec3f v, float tmin, float tmax, int trace_depth) {
     int nearest_idx = -1;
     float t_nearest = FLT_MAX;
     for (int i = 0; i < sizeof(balls) / sizeof(Ball); i++) {
@@ -181,8 +193,21 @@ Color calc_color(Vec3f v) {
         }
     }
     if (nearest_idx >= 0) {
+        Ball hit = balls[nearest_idx];
         Vec3f intersection = vec3f_add(start, vec3f_mul(t_nearest, v));
-        return ball_surface_color(&balls[nearest_idx], intersection, v);
+        Color local_color = ball_surface_color(&hit, intersection, v);
+        if (hit.reflective > 0 && trace_depth < MAX_TRACE_DEPTH) {
+            Vec3f refray = reflection(v, ball_norm(hit.center, intersection));
+            Color rcolor = calc_color(intersection, refray, EPSILON, FLT_MAX, trace_depth + 1);
+            float r = hit.reflective;
+            return (Color) {
+                r * rcolor.r + (1-r) * local_color.r,
+                r * rcolor.g + (1-r) * local_color.g,
+                r * rcolor.b + (1-r) * local_color.b,
+            };
+        } else {
+            return local_color;
+        }
     } else {
         return gBackgroupColor;
     }
@@ -194,11 +219,14 @@ int main() {
     int img_w = 800*2;
     int img_h = 800*2;
     Picture pic = new_picture(img_w, img_h);
+    Vec3f camera_pos = {.x = 0, .y = 0, .z = 0};
+    float tmin = 0.1;
+    float tmax = FLT_MAX;
     for (int x = 0; x < img_w; x++) {
         for (int y = 0; y < img_h; y++) {
             Vec2i screen_pos = {x, y};
             Vec3f v = screen_proj(img_w, img_h, screen_pos);
-            set_pixel(pic, screen_pos, calc_color(v));
+            set_pixel(pic, screen_pos, calc_color(camera_pos, v, tmin, tmax, 0));
         }
     }
     Picture newpic = picture_downscale_2x(pic);