Merge pull request #2330 from erinmaus/inverse-of

Add 'inverseOf' to love.Transform

src/modules/math/wrap_Transform.cpp

@@ -141,6 +141,15 @@ int w_Transform_inverse(lua_State *L)
 	return 1;
 }
 
+int w_Transform_inverseOf(lua_State *L)
+{
+	Transform *destination = luax_checktransform(L, 1);
+	Transform *source = luax_checktransform(L, 2);
+	destination->setMatrix(source->getMatrix().inverse());
+	lua_pushvalue(L, 1);
+	return 1;
+}
+
 int w_Transform_apply(lua_State *L)
 {
 	Transform *t = luax_checktransform(L, 1);
@@ -298,6 +307,7 @@ static const luaL_Reg functions[] =
 {
 	{ "clone", w_Transform_clone },
 	{ "inverse", w_Transform_inverse },
+	{ "inverseOf", w_Transform_inverseOf },
 	{ "apply", w_Transform_apply },
 	{ "isAffine2DTransform", w_Transform_isAffine2DTransform },
 	{ "translate", w_Transform_translate },

testing/tests/math.lua

@@ -145,6 +145,16 @@ love.test.math.Transform = function(test)
   px, py = transform:transformPoint(0, 0)
   test:assertCoords({-px, -py}, {ipx, ipy}, 'check inverse points transform')
 
+  -- check inverse and inverseOf produce same values
+  transform:reset()
+  transform:setTransformation(4, 4, math.pi / 2, 2, 2)
+  local inverseClone = transform:inverse()
+  local inverseDestinationTransform = love.math.newTransform()
+  inverseDestinationTransform:inverseOf(transform)
+  local opx1, opy1 = inverseClone:transformPoint(0, 0)
+  local opx2, opy2 = inverseDestinationTransform:transformPoint(0, 0)
+  test:assertCoords({opx1, opy1}, {opx2, opy2}, 'check inverse and inverseOf produce same values')
+
   -- check matrix manipulation
   transform:setTransformation(0, 0, 0, 1, 1, 0, 0, 0, 0)
   transform:translate(4, 4)