3 files changed, 42 insertions, 19 deletions

diff --git a/3dmath.c b/3dmath.c
index d729323..eb9c4a8 100644
--- a/3dmath.c
+++ b/3dmath.c
@@ -19,18 +19,29 @@ normalize(float x[3]) {
 }
 
 float
-sphere_intersect(float s[3], float d[3], float c[3], float r) {
+sphere_intersect(float y[3], float r[3], float s[3], float d[3], float c[3], float R) {
     int i;
-    float D;
-    float v[3];
+    float D, n[3], t, v[3];
 
     for(i = 0; i < 3; ++i)
         v[i] = s[i] - c[i];
 
-    D = POW2(dot(v, d)) - 4 * (dot(v, v) - POW2(r));
+    D = POW2(dot(v, d)) - (dot(v, v) - POW2(R));
 
     if(D < 0)
         return -1;
 
-    return 1;
+    t = -dot(v, d) - D;
+
+    for(i = 0; i < 3; ++i) {
+        y[i] = s[i] + t * d[i];
+        n[i] = y[i] - c[i];
+    }
+
+    normalize(n);
+
+    for(i = 0; i < 3; ++i)
+        r[i] = d[i] - 2 * dot(n, d) * n[i];
+
+    return t;
 }
diff --git a/3dmath.h b/3dmath.h
index 6714da5..4135f3b 100644
--- a/3dmath.h
+++ b/3dmath.h
@@ -1,3 +1,3 @@
 float dot(float x[3], float y[3]);
 void normalize(float x[3]);
-float sphere_intersect(float s[3], float d[3], float c[3], float r);
+float sphere_intersect(float y[3], float r[3], float s[3], float d[3], float c[3], float R);
diff --git a/ray.c b/ray.c
index 1eadb31..ccef64f 100644
--- a/ray.c
+++ b/ray.c
@@ -28,25 +28,40 @@ typedef struct {
 } Light;
 
 static unsigned char buffer[BUFFER_SIZE];
-static Object objects[2] = {{.position={0, 0, 2}, .radius=1, .diffuse={0, 0, .3}},
-                            {.position={-1.5, 0, -30}, .radius=.1, .diffuse={0, 0, .3}}};
+static Object objects[2] = {{.position={0, 0, -2}, .radius=1, .diffuse={0, 0, .3}},
+                            {.position={0, 0, -3}, .radius=1, .diffuse={0, 0, .3}}};
+//static Light lights[1] = {{.position={1, 0, 0}, .diffuse={0, 0, .3}}};
 
 static void
 trace(float s[3], float d[3], float pixel[3]) {
-    float t = sphere_intersect(s, d, objects[0].position, objects[0].radius);
+    int i;
+    float intensity, l[3], r[3], t, y[3];
 
-    //printf("%f.\n", objects[0].position[0]);
-    if(t > 0)
-        pixel[1] = .5;
-    else
-        pixel[2] = .5;
+    if(d[1] < 0) {
+        if((int)(d[0] / d[1] * 20) % 2)
+            pixel[0] += .1;
+
+        if((int)(d[1] / d[0] * 20) % 2)
+            pixel[1] += .1;
+    }
+
+    l[0] = -1;
+    l[1] = 1;
+    l[2] = 1;
+
+    normalize(l);
+
+    t = sphere_intersect(y, r, s, d, objects[0].position, objects[0].radius);
+
+    //if(t > 0)
+        //pixel[2] = dot(l, r);
 }
 
 static void
 display(void) {
+    static float s[3] = {0, 0, 0};
     int i, j;
     float x, y;
-    float s[3] = {0, 0, 0};
     float d[3];
     float pixel[3];
 
@@ -58,13 +73,10 @@ display(void) {
 
         d[0] = x / (WIDTH / 2);
         d[1] = y / (HEIGHT / 2);
-        d[2] = 1;
+        d[2] = -1;
 
         normalize(d);
 
-        //if(!(i % 256))
-            //printf("%f, %f, %f.\n", d[0], d[1], d[2]);
-
         memset(pixel, '\0', sizeof(pixel));
         trace(s, d, pixel);