mesa: Refactor viewport transform computation.

This is for preparation of ARB_clip_control.

v3:
Add comments.

Reviewed-by: Brian Paul <[email protected]>
Signed-off-by: Mathias Froehlich <[email protected]>

1 files changed, 10 insertions, 13 deletions

diff --git a/src/mesa/state_tracker/st_atom_viewport.c b/src/mesa/state_tracker/st_atom_viewport.c
index 7584f9b3d55..5b992084bd5 100644
--- a/src/mesa/state_tracker/st_atom_viewport.c
+++ b/src/mesa/state_tracker/st_atom_viewport.c
@@ -27,6 +27,7 @@
 
 
 #include "main/context.h"
+#include "main/viewport.h"
 #include "st_context.h"
 #include "st_atom.h"
 #include "pipe/p_context.h"
@@ -63,21 +64,17 @@ update_viewport( struct st_context *st )
     */
    for (i = 0; i < ctx->Const.MaxViewports; i++)
    {
-      GLfloat x = ctx->ViewportArray[i].X;
-      GLfloat y = ctx->ViewportArray[i].Y;
-      GLfloat z = ctx->ViewportArray[i].Near;
-      GLfloat half_width = ctx->ViewportArray[i].Width * 0.5f;
-      GLfloat half_height = ctx->ViewportArray[i].Height * 0.5f;
-      GLfloat half_depth = (GLfloat)(ctx->ViewportArray[i].Far - ctx->ViewportArray[i].Near) * 0.5f;
-      
-      st->state.viewport[i].scale[0] = half_width;
-      st->state.viewport[i].scale[1] = half_height * yScale;
-      st->state.viewport[i].scale[2] = half_depth;
+      double scale[3], translate[3];
+      _mesa_get_viewport_xform(ctx, i, scale, 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];
       st->state.viewport[i].scale[3] = 1.0;
 
-      st->state.viewport[i].translate[0] = half_width + x;
-      st->state.viewport[i].translate[1] = (half_height + y) * yScale + yBias;
-      st->state.viewport[i].translate[2] = half_depth + z;
+      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];
       st->state.viewport[i].translate[3] = 0.0;
    }