Fix #435 (for real this time). Unfixes #324.

Add a extern vec2 love_ScreenSize to the pixel effects that will
be (re)set upon PixelEffect::loadVolatile() and is used to flip
the fragment coordinate.

Unfixes #324 because canvases can have different dimensions than
the screen.

src/modules/graphics/Quad.h

@@ -50,11 +50,6 @@ public:
 
 	virtual void flip(bool x, bool y) = 0;
 
-	/**
-	 * Mirror texture coordinates around 0.5
-	 */
-	virtual void mirror(bool x, bool y) = 0;
-
 	/**
 	 * Gets a pointer to the vertices.
 	 **/

src/modules/graphics/opengl/Canvas.cpp

@@ -197,13 +197,13 @@ Canvas::Canvas(int width, int height)
 
 	// world coordinates
 	vertices[0].x = 0;
-	vertices[0].y = 0;
+	vertices[0].y = h;
 	vertices[1].x = 0;
-	vertices[1].y = h;
+	vertices[1].y = 0;
 	vertices[2].x = w;
-	vertices[2].y = h;
+	vertices[2].y = 0;
 	vertices[3].x = w;
-	vertices[3].y = 0;
+	vertices[3].y = h;
 
 	// texture coordinates
 	vertices[0].s = 0;
@@ -262,7 +262,7 @@ void Canvas::startGrab()
 	glLoadIdentity();
 
 	// Set up orthographic view (no depth)
-	glOrtho(0.0, width, height, 0.0, -1.0, 1.0);
+	glOrtho(0.0, width, 0.0, height, -1.0, 1.0);
 
 	// Switch back to modelview matrix
 	glMatrixMode(GL_MODELVIEW);
@@ -312,12 +312,10 @@ void Canvas::draw(float x, float y, float angle, float sx, float sy, float ox, f
 void Canvas::drawq(love::graphics::Quad *quad, float x, float y, float angle, float sx, float sy, float ox, float oy, float kx, float ky) const
 {
 	static Matrix t;
-	quad->mirror(false, true);
 	const vertex *v = quad->getVertices();
 
 	t.setTransformation(x, y, angle, sx, sy, ox, oy, kx, ky);
 	drawv(t, v);
-	quad->mirror(false, true);
 }
 
 love::image::ImageData *Canvas::getImageData(love::image::Image *image)
@@ -325,7 +323,6 @@ love::image::ImageData *Canvas::getImageData(love::image::Image *image)
 	int row = 4 * width;
 	int size = row * height;
 	GLubyte *pixels = new GLubyte[size];
-	GLubyte *screenshot = new GLubyte[size];
 
 	strategy->bindFBO(fbo);
 	glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
@@ -334,15 +331,8 @@ love::image::ImageData *Canvas::getImageData(love::image::Image *image)
 	else
 		strategy->bindFBO(0);
 
-	GLubyte *src = pixels - row;  // second line of source image
-	GLubyte *dst = screenshot + size;  // last row of destination image
+	love::image::ImageData *img = image->newImageData(width, height, (void *)pixels);
 
-	for (int i = 0; i < height; ++i)
-		memcpy(dst -= row, src += row, row);
-
-	love::image::ImageData *img = image->newImageData(width, height, (void *)screenshot);
-
-	delete[] screenshot;
 	delete[] pixels;
 
 	return img;

src/modules/graphics/opengl/PixelEffect.cpp

@@ -20,6 +20,7 @@
 
 #include "PixelEffect.h"
 #include "GLee.h"
+#include "Graphics.h"
 
 namespace
 {
@@ -134,6 +135,11 @@ bool PixelEffect::loadVolatile()
 	}
 
 	glDeleteShader(shader);
+
+	Graphics *instance = (Graphics*)Module::getInstance("love.graphics.opengl");
+	GLfloat screenSize[2] = {(float)instance->getWidth(), (float)instance->getHeight()};
+	sendFloat("love_ScreenSize", 2, screenSize, 1);
+
 	return true;
 }
 

src/modules/graphics/opengl/Quad.cpp

@@ -113,17 +113,6 @@ void Quad::flip(bool x, bool y)
 	}
 }
 
-void Quad::mirror(bool x, bool y)
-{
-	for (size_t i = 0; i < NUM_VERTICES; ++i)
-	{
-		if (x)
-			vertices[i].s = 1.0f - vertices[i].s;
-		if (y)
-			vertices[i].t = 1.0f - vertices[i].t;
-	}
-}
-
 const vertex *Quad::getVertices() const
 {
 	return vertices;

src/modules/graphics/opengl/Quad.h

@@ -54,7 +54,6 @@ public:
 	Viewport getViewport() const;
 
 	void flip(bool x, bool y);
-	void mirror(bool x, bool y);
 
 	/**
 	 * Gets a pointer to the vertices.