commit cb3d7d3831bc21becfe422c8e3ef00578075b2a6
author Sam Lantinga <slouken@libsdl.org> Wed Nov 13 21:50:59 2013 -0800
committer Sam Lantinga <slouken@libsdl.org> Wed Nov 13 21:50:59 2013 -0800
tree 28c1b7f58d6b603c2679fc715b24e81892f3bf1a
parent ee3f8b15d53d9c8ac745c840f56aa35d513f92ca

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

diff --git a/src/render/direct3d/SDL_render_d3d.c b/src/render/direct3d/SDL_render_d3d.c
index a4c6027..38fb6d0 100644
--- a/src/render/direct3d/SDL_render_d3d.c
+++ b/src/render/direct3d/SDL_render_d3d.c
@@ -1635,22 +1635,26 @@
     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;

src/render/opengl/SDL_render_gl.c

diff --git a/src/render/opengl/SDL_render_gl.c b/src/render/opengl/SDL_render_gl.c
index 94914ea..bb789c1 100644
--- a/src/render/opengl/SDL_render_gl.c
+++ b/src/render/opengl/SDL_render_gl.c
@@ -1250,22 +1250,26 @@
     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;