port invert and transformMat4 from gl-matrix

src/mbgl/util/mat4.cpp

@@ -45,6 +45,53 @@ void matrix::identity(mat4& out) {
     out[15] = 1.0f;
 }
 
+bool matrix::invert(mat4& out, mat4& a) {
+    float a00 = a[0], a01 = a[1], a02 = a[2], a03 = a[3],
+          a10 = a[4], a11 = a[5], a12 = a[6], a13 = a[7],
+          a20 = a[8], a21 = a[9], a22 = a[10], a23 = a[11],
+          a30 = a[12], a31 = a[13], a32 = a[14], a33 = a[15],
+
+          b00 = a00 * a11 - a01 * a10,
+          b01 = a00 * a12 - a02 * a10,
+          b02 = a00 * a13 - a03 * a10,
+          b03 = a01 * a12 - a02 * a11,
+          b04 = a01 * a13 - a03 * a11,
+          b05 = a02 * a13 - a03 * a12,
+          b06 = a20 * a31 - a21 * a30,
+          b07 = a20 * a32 - a22 * a30,
+          b08 = a20 * a33 - a23 * a30,
+          b09 = a21 * a32 - a22 * a31,
+          b10 = a21 * a33 - a23 * a31,
+          b11 = a22 * a33 - a23 * a32,
+
+          // Calculate the determinant
+          det = b00 * b11 - b01 * b10 + b02 * b09 + b03 * b08 - b04 * b07 + b05 * b06;
+
+    if (!det) {
+        return true;
+    }
+    det = 1.0 / det;
+
+    out[0] = (a11 * b11 - a12 * b10 + a13 * b09) * det;
+    out[1] = (a02 * b10 - a01 * b11 - a03 * b09) * det;
+    out[2] = (a31 * b05 - a32 * b04 + a33 * b03) * det;
+    out[3] = (a22 * b04 - a21 * b05 - a23 * b03) * det;
+    out[4] = (a12 * b08 - a10 * b11 - a13 * b07) * det;
+    out[5] = (a00 * b11 - a02 * b08 + a03 * b07) * det;
+    out[6] = (a32 * b02 - a30 * b05 - a33 * b01) * det;
+    out[7] = (a20 * b05 - a22 * b02 + a23 * b01) * det;
+    out[8] = (a10 * b10 - a11 * b08 + a13 * b06) * det;
+    out[9] = (a01 * b08 - a00 * b10 - a03 * b06) * det;
+    out[10] = (a30 * b04 - a31 * b02 + a33 * b00) * det;
+    out[11] = (a21 * b02 - a20 * b04 - a23 * b00) * det;
+    out[12] = (a11 * b07 - a10 * b09 - a12 * b06) * det;
+    out[13] = (a00 * b09 - a01 * b07 + a02 * b06) * det;
+    out[14] = (a31 * b01 - a30 * b03 - a32 * b00) * det;
+    out[15] = (a20 * b03 - a21 * b01 + a22 * b00) * det;
+
+    return false;
+}
+
 void matrix::ortho(mat4& out, double left, double right, double bottom, double top, double near, double far) {
     double lr = 1.0f / (left - right),
           bt = 1.0f / (bottom - top),

src/mbgl/util/vec4.cpp

@@ -0,0 +1,33 @@
+// This is an incomplete port of http://glmatrix.net/
+//
+// Copyright (c) 2013 Brandon Jones, Colin MacKenzie IV
+//
+// This software is provided 'as-is', without any express or implied warranty.
+// In no event will the authors be held liable for any damages arising from the
+// use of this software.
+//
+// Permission is granted to anyone to use this software for any purpose,
+// including commercial applications, and to alter it and redistribute it
+// freely, subject to the following restrictions:
+//
+// 1. The origin of this software must not be misrepresented; you must not claim
+//    that you wrote the original software. If you use this software in a
+//    product, an acknowledgment in the product documentation would be
+//    appreciated but is not required.
+//
+// 2. Altered source versions must be plainly marked as such, and must not be
+//    misrepresented as being the original software.
+//
+// 3. This notice may not be removed or altered from any source distribution.
+
+#include <mbgl/util/vec4.hpp>
+
+using namespace mbgl;
+
+void matrix::transformMat4(vec4& out, vec4& a, mat4& m) {
+    float x = a[0], y = a[1], z = a[2], w = a[3];
+    out[0] = m[0] * x + m[4] * y + m[8] * z + m[12] * w;
+    out[1] = m[1] * x + m[5] * y + m[9] * z + m[13] * w;
+    out[2] = m[2] * x + m[6] * y + m[10] * z + m[14] * w;
+    out[3] = m[3] * x + m[7] * y + m[11] * z + m[15] * w;
+}

src/mbgl/util/vec4.hpp

@@ -0,0 +1,40 @@
+// This is an incomplete port of http://glmatrix.net/
+//
+// Copyright (c) 2013 Brandon Jones, Colin MacKenzie IV
+//
+// This software is provided 'as-is', without any express or implied warranty.
+// In no event will the authors be held liable for any damages arising from the
+// use of this software.
+//
+// Permission is granted to anyone to use this software for any purpose,
+// including commercial applications, and to alter it and redistribute it
+// freely, subject to the following restrictions:
+//
+// 1. The origin of this software must not be misrepresented; you must not claim
+//    that you wrote the original software. If you use this software in a
+//    product, an acknowledgment in the product documentation would be
+//    appreciated but is not required.
+//
+// 2. Altered source versions must be plainly marked as such, and must not be
+//    misrepresented as being the original software.
+//
+// 3. This notice may not be removed or altered from any source distribution.
+
+#ifndef MBGL_UTIL_VEC4
+#define MBGL_UTIL_VEC4
+
+#include <array>
+#include <mbgl/util/mat4.hpp>
+
+namespace mbgl {
+
+namespace matrix {
+
+typedef std::array<double, 4> vec4;
+
+void transformMat4(vec4& out, vec4& a, mat4& m);
+
+}
+}
+
+#endif