glsl: add ir_emit_vertex and ir_end_primitive instruction types

[mesa.git] / src / mesa / state_tracker / st_atom_viewport.c

diff --git a/src/mesa/state_tracker/st_atom_viewport.c b/src/mesa/state_tracker/st_atom_viewport.c
index 0b6c34ca2cbec9ac7d919e2faf7a683677e3d779..133cc49eaf05798b34d7d15dee18e595c261dd87 100644 (file)
--- a/src/mesa/state_tracker/st_atom_viewport.c
+++ b/src/mesa/state_tracker/st_atom_viewport.c
@@ -41,16 +41,20 @@
 static void
 update_viewport( struct st_context *st )
 {
-   GLcontext *ctx = st->ctx;
+   struct gl_context *ctx = st->ctx;
    GLfloat yScale, yBias;
 
    /* _NEW_BUFFERS
     */
    if (st_fb_orientation(ctx->DrawBuffer) == 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;
    }