Implement the bezier position function.

1 files changed, 17 insertions, 2 deletions

diff --git a/src/bezier.cpp b/src/bezier.cpp
index e3fa37d..6f42a30 100755
--- a/src/bezier.cpp
+++ b/src/bezier.cpp
@@ -21,14 +21,29 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include <cmath>
 #include "bezier.h"
 
+static float fact(float n)
+{
+	return n == 0 ? 1 : n * fact(n - 1);
+}
+
+/* The bezier basis function, assuming n = 3 */
+static float b(int i, float t)
+{
+	return 6/(fact(i) * fact(3 - i)) * powf(t, i) * powf(1 - t, 3 - i);
+}
+
 GLUvec4
 bezier_curve::position(float t) const
 {
-	/* FINISHME: Implement this function.
-	 */
 	GLUvec4 result(0.0, 0.0, 0.0, 0.0);
 
+	/* Note that n = 3. */
+	for (int i = 0; i < 4; i++) {
+		result += b(i, t) * p[i];
+	}
+
 	return result;
 }