gallium: convert rasterizer state to use gl-style front/back concepts

Use front/back instead of cw/ccw throughout.
Also, use offset_point/line/fill instead of offset_cw/ccw.

Brings gallium representation of this state into line with its main
user, and also what turns out to be the most common hardware
representation.

This fixes a long-standing bias in the interface towards the
architecture of the software rasterizer.

2 files changed, 7 insertions, 37 deletions

diff --git a/src/gallium/drivers/softpipe/sp_context.h b/src/gallium/drivers/softpipe/sp_context.h
index aa696257688..b3d3fe620fd 100644
--- a/src/gallium/drivers/softpipe/sp_context.h
+++ b/src/gallium/drivers/softpipe/sp_context.h
@@ -109,6 +109,9 @@ struct softpipe_context {
    /** The reduced version of the primitive supplied by the state tracker */
    unsigned reduced_api_prim;
 
+   /** Derived information about which winding orders to cull */
+   unsigned cull_mode;
+
    /**
     * The reduced primitive after unfilled triangles, wide-line decomposition,
     * etc, are taken into account.  This is the primitive type that's actually
diff --git a/src/gallium/drivers/softpipe/sp_setup.c b/src/gallium/drivers/softpipe/sp_setup.c
index 35ef9e698d5..ca02d4df489 100644
--- a/src/gallium/drivers/softpipe/sp_setup.c
+++ b/src/gallium/drivers/softpipe/sp_setup.c
@@ -111,34 +111,12 @@ struct setup_context {
    uint numFragsWritten;  /**< per primitive */
 #endif
 
-   unsigned winding;		/* which winding to cull */
    unsigned nr_vertex_attrs;
 };
 
 
 
 
-/**
- * Do triangle cull test using tri determinant (sign indicates orientation)
- * \return true if triangle is to be culled.
- */
-static INLINE boolean
-cull_tri(const struct setup_context *setup, float det)
-{
-   if (det != 0) {   
-      /* if (det < 0 then Z points toward camera and triangle is 
-       * counter-clockwise winding.
-       */
-      unsigned winding = (det < 0) ? PIPE_WINDING_CCW : PIPE_WINDING_CW;
-
-      if ((winding & setup->winding) == 0)
-	 return FALSE;
-   }
-
-   /* Culled:
-    */
-   return TRUE;
-}
 
 
 
@@ -393,8 +371,8 @@ setup_sort_vertices(struct setup_context *setup,
     * 0 = front-facing, 1 = back-facing
     */
    setup->facing = 
-      ((det > 0.0) ^ 
-       (setup->softpipe->rasterizer->front_winding == PIPE_WINDING_CW));
+      ((det < 0.0) ^ 
+       (setup->softpipe->rasterizer->front_ccw));
 
    /* Prepare pixel offset for rasterisation:
     *  - pixel center (0.5, 0.5) for GL, or
@@ -832,8 +810,8 @@ sp_setup_tri(struct setup_context *setup,
    setup->numFragsWritten = 0;
 #endif
 
-   if (cull_tri( setup, det ))
-      return;
+   /* Culling already done by draw module.
+    */
 
    if (!setup_sort_vertices( setup, det, v0, v1, v2 ))
       return;
@@ -1418,17 +1396,6 @@ sp_setup_prepare(struct setup_context *setup)
    setup->nr_vertex_attrs = draw_num_shader_outputs(sp->draw);
 
    sp->quad.first->begin( sp->quad.first );
-
-   if (sp->reduced_api_prim == PIPE_PRIM_TRIANGLES &&
-       sp->rasterizer->fill_cw == PIPE_POLYGON_MODE_FILL &&
-       sp->rasterizer->fill_ccw == PIPE_POLYGON_MODE_FILL) {
-      /* we'll do culling */
-      setup->winding = sp->rasterizer->cull_mode;
-   }
-   else {
-      /* 'draw' will do culling */
-      setup->winding = PIPE_WINDING_NONE;
-   }
 }