X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=util.cpp;h=2176786978544994fcb733a4a2bea5f6fb9f77f5;hp=c18f00949d1e2d1bca75bd3945ac2fcbc82e6811;hb=758f632c42befae7f2b7af137554429fa544d4cb;hpb=a592c55caca0fb654bad4ec43b84c46abcee21c2

diff --git a/util.cpp b/util.cpp
index c18f009..2176786 100644
--- a/util.cpp
+++ b/util.cpp
@@ -88,3 +88,45 @@ GLhandleARB compile_shader(const std::string &shader_src, GLenum type)
 	return obj;
 }
 
+void multiply_3x3_matrices(const Matrix3x3 a, const Matrix3x3 b, Matrix3x3 result)
+{
+        result[0] = a[0] * b[0] + a[3] * b[1] + a[6] * b[2];
+        result[1] = a[1] * b[0] + a[4] * b[1] + a[7] * b[2];
+        result[2] = a[2] * b[0] + a[5] * b[1] + a[8] * b[2];
+
+        result[3] = a[0] * b[3] + a[3] * b[4] + a[6] * b[5];
+        result[4] = a[1] * b[3] + a[4] * b[4] + a[7] * b[5];
+        result[5] = a[2] * b[3] + a[5] * b[4] + a[8] * b[5];
+
+        result[6] = a[0] * b[6] + a[3] * b[7] + a[6] * b[8];
+        result[7] = a[1] * b[6] + a[4] * b[7] + a[7] * b[8];
+        result[8] = a[2] * b[6] + a[5] * b[7] + a[8] * b[8];
+}
+
+void invert_3x3_matrix(const Matrix3x3 m, Matrix3x3 result)
+{
+	double inv_det = 1.0 / (
+		m[6] * m[1] * m[5] - m[6] * m[2] * m[4] -
+		m[3] * m[1] * m[8] + m[3] * m[2] * m[7] +
+		m[0] * m[4] * m[8] - m[0] * m[5] * m[7]);
+
+	result[0] = inv_det * (m[4] * m[8] - m[5] * m[7]);
+	result[1] = inv_det * (m[2] * m[7] - m[1] * m[8]);
+	result[2] = inv_det * (m[1] * m[5] - m[2] * m[4]);
+
+	result[3] = inv_det * (m[6] * m[5] - m[3] * m[8]);
+	result[4] = inv_det * (m[0] * m[8] - m[6] * m[2]);
+	result[5] = inv_det * (m[3] * m[2] - m[0] * m[5]);
+
+	result[6] = inv_det * (m[3] * m[7] - m[6] * m[4]);
+	result[7] = inv_det * (m[6] * m[1] - m[0] * m[7]);
+	result[8] = inv_det * (m[0] * m[4] - m[3] * m[1]);
+}
+
+void print_3x3_matrix(const Matrix3x3 m)
+{
+	printf("%6.4f %6.4f %6.4f\n", m[0], m[3], m[6]);
+	printf("%6.4f %6.4f %6.4f\n", m[1], m[4], m[7]);
+	printf("%6.4f %6.4f %6.4f\n", m[2], m[5], m[8]);
+	printf("\n");
+}