From cb3d7d3831bc21becfe422c8e3ef00578075b2a6 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Wed, 13 Nov 2013 21:50:59 -0800
Subject: [PATCH] Diagonal flipping with RenderCopyEx

Ivan Rubinson

As it turns out, it was impossible to render a texture flipped diagonally (both vertically and horizontally) with one RenderCopyEx call.
With help from #SDL @ freenode, we came up with a fix.
---
 src/render/direct3d/SDL_render_d3d.c | 36 +++++++++++++++-------------
 src/render/opengl/SDL_render_gl.c    | 32 ++++++++++++++-----------
 2 files changed, 38 insertions(+), 30 deletions(-)

diff --git a/src/render/direct3d/SDL_render_d3d.c b/src/render/direct3d/SDL_render_d3d.c
index a4c602757..38fb6d082 100644
--- a/src/render/direct3d/SDL_render_d3d.c
+++ b/src/render/direct3d/SDL_render_d3d.c
@@ -1635,22 +1635,26 @@ D3D_RenderCopyEx(SDL_Renderer * renderer, SDL_Texture * texture,
     centerx = center->x;
     centery = center->y;
 
-    if (flip & SDL_FLIP_HORIZONTAL) {
-        minx = dstrect->w - centerx - 0.5f;
-        maxx = -centerx - 0.5f;
-    }
-    else {
-        minx = -centerx - 0.5f;
-        maxx = dstrect->w - centerx - 0.5f;
-    }
-
-    if (flip & SDL_FLIP_VERTICAL) {
-        miny = dstrect->h - centery - 0.5f;
-        maxy = -centery - 0.5f;
-    }
-    else {
-        miny = -centery - 0.5f;
-        maxy = dstrect->h - centery - 0.5f;
+    if ((flip & SDL_FLIP_VERTICAL) && (flip & SDL_FLIP_HORIZONTAL)) {
+        miny = dstrect->h - centery;
+        maxy = -centery;
+        minx = dstrect->w - centerx;
+        maxx = -centerx;
+    } else if (flip & SDL_FLIP_HORIZONTAL) {
+        miny = -centery;
+        maxy = dstrect->h - centery;
+        minx = dstrect->w - centerx;
+        maxx = -centerx;
+    } else if (flip & SDL_FLIP_VERTICAL) {
+        miny = dstrect->h - centery;
+        maxy = -centery;
+        minx = -centerx;
+        maxx = dstrect->w - centerx;
+    } else {
+        miny = -centery;
+        maxy = dstrect->h - centery;
+        minx = -centerx;
+        maxx = dstrect->w - centerx;
     }
 
     minu = (float) srcrect->x / texture->w;
diff --git a/src/render/opengl/SDL_render_gl.c b/src/render/opengl/SDL_render_gl.c
index 94914ead1..bb789c138 100644
--- a/src/render/opengl/SDL_render_gl.c
+++ b/src/render/opengl/SDL_render_gl.c
@@ -1250,22 +1250,26 @@ GL_RenderCopyEx(SDL_Renderer * renderer, SDL_Texture * texture,
     centerx = center->x;
     centery = center->y;
 
-    if (flip & SDL_FLIP_HORIZONTAL) {
-        minx =  dstrect->w - centerx;
-        maxx = -centerx;
-    }
-    else {
-        minx = -centerx;
-        maxx =  dstrect->w - centerx;
-    }
-
-    if (flip & SDL_FLIP_VERTICAL) {
-        miny =  dstrect->h - centery;
+    if ((flip & SDL_FLIP_VERTICAL) && (flip & SDL_FLIP_HORIZONTAL)) {
+        miny = dstrect->h - centery;
         maxy = -centery;
-    }
-    else {
+        minx = dstrect->w - centerx;
+        maxx = -centerx;
+    } else if (flip & SDL_FLIP_HORIZONTAL) {
         miny = -centery;
-        maxy =  dstrect->h - centery;
+        maxy = dstrect->h - centery;
+        minx = dstrect->w - centerx;
+        maxx = -centerx;
+    } else if (flip & SDL_FLIP_VERTICAL) {
+        miny = dstrect->h - centery;
+        maxy = -centery;
+        minx = -centerx;
+        maxx = dstrect->w - centerx;
+    } else {
+        miny = -centery;
+        maxy = dstrect->h - centery;
+        minx = -centerx;
+        maxx = dstrect->w - centerx;
     }
 
     minu = (GLfloat) srcrect->x / texture->w;