Added Transform objects to love.math (resolves issue #1228).

- Added love.math.newTransform.
- Added love.graphics.applyTransform and love.graphics.replaceTransform.
- love.graphics.draw/print/printf, Text:add/addf, and SpriteBatch:add can accept a Transform argument.
- love.graphics.push can accept an optional Transform as a second argument, which will apply the Transform after pushing the matrix stack,
- Shader:send can accept Transform objects when sending to a mat4 uniform variable.

--HG--
branch : minor

src/modules/math/Transform.h

@@ -0,0 +1,83 @@
+/**
+ * Copyright (c) 2006-2016 LOVE Development Team
+ *
+ * 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.
+ **/
+
+#pragma once
+
+// LOVE
+#include "common/Object.h"
+#include "common/Matrix.h"
+#include "common/Vector.h"
+
+namespace love
+{
+namespace math
+{
+
+class Transform : public Object
+{
+public:
+
+	Transform();
+	Transform(const Matrix4 &m);
+	Transform(float x, float y, float a, float sx, float sy, float ox, float oy, float kx, float ky);
+
+	virtual ~Transform();
+
+	Transform *clone();
+	Transform *inverse();
+
+	void apply(Transform *other);
+
+	void translate(float x, float y);
+	void rotate(float angle);
+	void scale(float x, float y);
+	void shear(float x, float y);
+
+	void reset();
+	void setTransformation(float x, float y, float a, float sx, float sy, float ox, float oy, float kx, float ky);
+
+	love::Vector transformPoint(love::Vector p) const;
+	love::Vector inverseTransformPoint(love::Vector p);
+
+	const Matrix4 &getMatrix() const;
+	void setMatrix(const Matrix4 &m);
+
+private:
+
+	inline const Matrix4 &getInverseMatrix()
+	{
+		if (inverseDirty)
+		{
+			inverseDirty = false;
+			inverseMatrix = matrix.inverse();
+		}
+
+		return inverseMatrix;
+	}
+	
+	Matrix4 matrix;
+	bool inverseDirty;
+	Matrix4 inverseMatrix;
+
+}; // Transform
+
+
+} // math
+} // love