From 7e071db6bee659dbd2b4261830f4e2f10bc8ba33 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Stensg=C3=A5rd?= <mastensg@ping.uio.no>
Date: Tue, 19 Oct 2010 00:20:35 +0200
Subject: Fail.

---
 3dmath.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 3dmath.c

(limited to '3dmath.c')

diff --git a/3dmath.c b/3dmath.c
new file mode 100644
index 0000000..d729323
--- /dev/null
+++ b/3dmath.c
@@ -0,0 +1,36 @@
+#include <math.h>
+
+#define POW2(x) ((x) * (x))
+
+float
+dot(float x[3], float y[3]) {
+    return x[0] * y[0] + x[1] * y[1] + x[2] * y[2];
+}
+
+void
+normalize(float x[3]) {
+    float len;
+    int i;
+
+    len = sqrt(dot(x, x));
+
+    for(i = 0; i < 3; ++i)
+        x[i] /= len;
+}
+
+float
+sphere_intersect(float s[3], float d[3], float c[3], float r) {
+    int i;
+    float D;
+    float 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));
+
+    if(D < 0)
+        return -1;
+
+    return 1;
+}
-- 
cgit v1.2.3