move viewport Y inversion to state tracker

1 files changed, 21 insertions, 36 deletions

diff --git a/src/mesa/state_tracker/st_atom_viewport.c b/src/mesa/state_tracker/st_atom_viewport.c
index ac91f628aa..1307cbb6d2 100644
--- a/src/mesa/state_tracker/st_atom_viewport.c
+++ b/src/mesa/state_tracker/st_atom_viewport.c
@@ -33,9 +33,6 @@
 #include "st_atom.h"
 
 
-
-
-
 /**
  * Update the viewport transformation matrix.  Depends on:
  *  - viewport pos/size
@@ -45,49 +42,37 @@
 static void update_viewport( struct st_context *st )
 {
    GLcontext *ctx = st->ctx;
-   const GLframebuffer *DrawBuffer = ctx->DrawBuffer;
-   GLfloat yScale = 1.0;
-   GLfloat yBias = 0.0;
+   GLfloat yScale, yBias;
 
-   /* _NEW_BUFFERS
+   /* Negate Y scale to flip image vertically.
+    * The NDC Y coords prior to viewport transformation are in the range
+    * [y=-1=bottom, y=1=top]
+    * Hardware window coords are in the range [y=0=top, y=H-1=bottom] where H
+    * is the window height.
+    * Use the viewport transformation to invert Y.
     */
-   if (DrawBuffer) {
 
-#if 0
-      if (DrawBuffer->Name) {
-	 /* User created FBO */
-	 struct st_renderbuffer *irb
-	    = st_renderbuffer(DrawBuffer->_ColorDrawBuffers[0][0]);
-	 if (irb && !irb->RenderToTexture) {
-	    /* y=0=top */
-	    yScale = -1.0;
-	    yBias = irb->Base.Height;
-	 }
-	 else {
-	    /* y=0=bottom */
-	    yScale = 1.0;
-	    yBias = 0.0;
-	 }
-      }
-      else 
-      {
-	 /* window buffer, y=0=top */
-	 yScale = -1.0;
-	 yBias = DrawBuffer->Height;
-      }
-#endif
+   /* _NEW_BUFFERS
+    */
+   if (ctx->DrawBuffer) {
+      yScale = -1;
+      yBias = ctx->DrawBuffer->Height ;
+   }
+   else {
+      /* we won't be rendering anything */
+      yScale = 1.0;
+      yBias = 0.0;
    }
 
+   /* _NEW_VIEWPORT 
+    */
    {
-      /* _NEW_VIEWPORT 
-       */
       GLfloat x = ctx->Viewport.X;
       GLfloat y = ctx->Viewport.Y;
       GLfloat z = ctx->Viewport.Near;
       GLfloat half_width = ctx->Viewport.Width / 2.0;
       GLfloat half_height = ctx->Viewport.Height / 2.0;
       GLfloat half_depth = (ctx->Viewport.Far - ctx->Viewport.Near) / 2.0;
-
       struct pipe_viewport_state vp;
       
       vp.scale[0] = half_width;
@@ -95,9 +80,9 @@ static void update_viewport( struct st_context *st )
       vp.scale[2] = half_depth;
       vp.scale[3] = 1.0;
 
-      vp.translate[0] = (half_width + x);
+      vp.translate[0] = half_width + x;
       vp.translate[1] = (half_height + y) * yScale + yBias;
-      vp.translate[2] = (half_depth + z);
+      vp.translate[2] = half_depth + z;
       vp.translate[3] = 0.0;
 
       if (memcmp(&vp, &st->state.viewport, sizeof(vp)) != 0) {