st/mesa: simplify st_update_viewport

Reviewed-by: Nicolai Hähnle <[email protected]>

1 files changed, 10 insertions, 25 deletions

diff --git a/src/mesa/state_tracker/st_atom_viewport.c b/src/mesa/state_tracker/st_atom_viewport.c
index 1fc8908f9f7..abf5faa0bc3 100644
--- a/src/mesa/state_tracker/st_atom_viewport.c
+++ b/src/mesa/state_tracker/st_atom_viewport.c
@@ -43,37 +43,22 @@ void
 st_update_viewport( struct st_context *st )
 {
    struct gl_context *ctx = st->ctx;
-   GLfloat yScale, yBias;
    unsigned i;
-   /* _NEW_BUFFERS
-    */
-   if (st->state.fb_orientation == Y_0_TOP) {
-      /* Drawing to a window.  The corresponding gallium surface uses
-       * Y=0=TOP but OpenGL is Y=0=BOTTOM.  So we need to invert the viewport.
-       */
-      yScale = -1;
-      yBias = (GLfloat)ctx->DrawBuffer->Height;
-   }
-   else {
-      /* Drawing to an FBO where Y=0=BOTTOM, like OpenGL - don't invert */
-      yScale = 1.0;
-      yBias = 0.0;
-   }
 
    /* _NEW_VIEWPORT 
     */
-   for (i = 0; i < ctx->Const.MaxViewports; i++)
-   {
-      float scale[3], translate[3];
-      _mesa_get_viewport_xform(ctx, i, scale, translate);
+   for (i = 0; i < ctx->Const.MaxViewports; i++) {
+      float *scale = st->state.viewport[i].scale;
+      float *translate = st->state.viewport[i].translate;
 
-      st->state.viewport[i].scale[0] = scale[0];
-      st->state.viewport[i].scale[1] = scale[1] * yScale;
-      st->state.viewport[i].scale[2] = scale[2];
+      _mesa_get_viewport_xform(ctx, i, scale, translate);
 
-      st->state.viewport[i].translate[0] = translate[0];
-      st->state.viewport[i].translate[1] = translate[1] * yScale + yBias;
-      st->state.viewport[i].translate[2] = translate[2];
+      /* _NEW_BUFFERS */
+      /* Drawing to a window where the coordinate system is upside down. */
+      if (st->state.fb_orientation == Y_0_TOP) {
+         scale[1] *= -1;
+         translate[1] = st->state.fb_height - translate[1];
+      }
    }
 
    cso_set_viewport(st->cso_context, &st->state.viewport[0]);