Refactor mat4x4_look_at to reuse internal functions and data types.

1 files changed, 21 insertions, 42 deletions

diff --git a/linmath.h b/linmath.h
index 7333d9a..1c147a8 100644
--- a/linmath.h
+++ b/linmath.h
@@ -357,56 +357,35 @@ static inline void mat4x4_perspective(mat4x4 m, float y_fov_in_degrees, float as
 	m[3][2] = -((2.0f * f * n) / (f - n));
 	m[3][3] = 0.0f;
 }
-static inline void mat4x4_look_at(mat4x4 m,
-		float eyeX, float eyeY, float eyeZ,
-		float centerX, float centerY, float centerZ,
-		float upX, float upY, float upZ)
+static inline void mat4x4_look_at(mat4x4 m, vec3 eye, vec3 center, vec3 up)
 {
 	/* Adapted from Android's OpenGL Matrix.java. */
 	// See the OpenGL GLUT documentation for gluLookAt for a description
 	// of the algorithm. We implement it in a straightforward way:
+	vec3 f;
+	vec3_sub(f, center, eye);	
+	vec3_norm(f, f);	
+	
+	vec3 s;
+	vec3_mul_cross(s, f, up);
+	vec3_norm(s, s);
+
+	vec3 u;
+	vec3_mul_cross(u, s, f);
 
-	float fx = centerX - eyeX;
-	float fy = centerY - eyeY;
-	float fz = centerZ - eyeZ;
-
-	// Normalize f
-	vec3 f_vec = {fx, fy, fz};
-	float rlf = 1.0f / vec3_len(f_vec);
-	fx *= rlf;
-	fy *= rlf;
-	fz *= rlf;
-
-	// compute s = f x up (x means "cross product")
-	float sx = fy * upZ - fz * upY;
-	float sy = fz * upX - fx * upZ;
-	float sz = fx * upY - fy * upX;
-
-	// and normalize s
-	vec3 s_vec = {sx, sy, sz};
-	float rls = 1.0f / vec3_len(s_vec);
-	sx *= rls;
-	sy *= rls;
-	sz *= rls;
-
-	// compute u = s x f
-	float ux = sy * fz - sz * fy;
-	float uy = sz * fx - sx * fz;
-	float uz = sx * fy - sy * fx;
-
-	m[0][0] = sx;
-	m[0][1] = ux;
-	m[0][2] = -fx;
+	m[0][0] = s[0];
+	m[0][1] = u[0];
+	m[0][2] = -f[0];
 	m[0][3] = 0.0f;
 
-	m[1][0] = sy;
-	m[1][1] = uy;
-	m[1][2] = -fy;
+	m[1][0] = s[1];
+	m[1][1] = u[1];
+	m[1][2] = -f[1];
 	m[1][3] = 0.0f;
 
-	m[2][0] = sz;
-	m[2][1] = uz;
-	m[2][2] = -fz;
+	m[2][0] = s[2];
+	m[2][1] = u[2];
+	m[2][2] = -f[2];
 	m[2][3] = 0.0f;
 
 	m[3][0] = 0.0f;
@@ -414,7 +393,7 @@ static inline void mat4x4_look_at(mat4x4 m,
 	m[3][2] = 0.0f;
 	m[3][3] = 1.0f;
 
-	mat4x4_translate_in_place(m, -eyeX, -eyeY, -eyeZ);
+	mat4x4_translate_in_place(m, -eye[0], -eye[1], -eye[2]);
 }
 
 typedef float quat[4];