Implement bone matrix computation

linear_alg.c

@@ -74,3 +74,60 @@ mat4_t mat4_perspective(float aspect, float fov, float near, float far)
 		{ 0, 0, -far * near / (far - near), 0 },
 	};
 }
+
+mat4_t mat4_translate_vec3(vec3_t v)
+{
+	return (mat4_t) {
+		{ 1, 0, 0, 0 },
+		{ 0, 1, 0, 0 },
+		{ 0, 0, 1, 0 },
+		{ v.x, v.y, v.z, 1 },
+	};
+}
+
+mat4_t mat4_scale_vec3(vec3_t v)
+{
+	return (mat4_t) {
+		{ v.x, 0, 0, 0 },
+		{ 0, v.y, 0, 0 },
+		{ 0, 0, v.z, 0 },
+		{ 0, 0, 0, 1 },
+	};
+}
+
+mat4_t mat4_rotate_quaternion(vec4_t q)
+{
+	const float xx = q.x * q.x;
+	const float xy = q.x * q.y;
+	const float xz = q.x * q.z;
+	const float xw = q.x * q.w;
+
+	const float yy = q.y * q.y;
+	const float yz = q.y * q.z;
+	const float yw = q.y * q.w;
+
+	const float zz = q.z * q.z;
+	const float zw = q.z * q.w;
+
+	return (mat4_t) {
+		{
+		    1 - 2 * (yy + zz),
+		    2 * (xy + zw),
+		    2 * (xz - yw),
+		    0,
+		},
+		{
+		    2 * (xy - zw),
+		    1 - 2 * (xx + zz),
+		    2 * (yz + xw),
+		    0,
+		},
+		{
+		    2 * (xz + yw),
+		    2 * (yz - xw),
+		    1 - 2 * (xx + yy),
+		    0,
+		},
+		{ 0, 0, 0, 1 },
+	};
+}