From 1475d74cfba634cf24da30e48fe66de9c2d75d55 Mon Sep 17 00:00:00 2001
From: Brian <brian.paul@tungstengraphics.com>
Date: Tue, 24 Jul 2007 14:44:44 -0600
Subject: [PATCH] Compute need_z and need_w properly and use the correct
 const/linear/perspective interpolation in shade_quad().

---
 src/mesa/pipe/softpipe/sp_quad_fs.c       | 32 +++++++++++++++----------------
 src/mesa/pipe/softpipe/sp_state_derived.c | 21 +++++++++++++++++++-
 2 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/src/mesa/pipe/softpipe/sp_quad_fs.c b/src/mesa/pipe/softpipe/sp_quad_fs.c
index 846c330..5269924 100644
--- a/src/mesa/pipe/softpipe/sp_quad_fs.c
+++ b/src/mesa/pipe/softpipe/sp_quad_fs.c
@@ -121,12 +121,11 @@ static INLINE void pinterp( struct exec_machine *exec,
 static void
 shade_quad( struct quad_stage *qs, struct quad_header *quad )
 {
-   struct softpipe_context *softpipe = qs->softpipe;
+   const struct softpipe_context *softpipe = qs->softpipe;
    struct exec_machine exec;
-   GLfloat fx = quad->x0;
-   GLfloat fy = quad->y0;
+   const GLfloat fx = quad->x0;
+   const GLfloat fy = quad->y0;
    GLuint i, j;
-   GLboolean need_z = softpipe->depth_test.enabled; /* XXX hack */
 
    exec.coef = quad->coef;
 
@@ -142,27 +141,22 @@ shade_quad( struct quad_stage *qs, struct quad_header *quad )
    exec.attr[FRAG_ATTRIB_WPOS][1][2] = fy + 1.0;
    exec.attr[FRAG_ATTRIB_WPOS][1][3] = fy + 1.0;
 
-   /* Z and W are done by linear interpolation:
-    * XXX we'll probably have to use integers for Z
-    */
-   if (/*softpipe->*/need_z) {
+   /* Z and W are done by linear interpolation */
+   if (softpipe->need_z) {
       linterp(&exec, 0, 2);   /* attr[0].z */
    }
 
    if (softpipe->need_w) {
       linterp(&exec, 0, 3);  /* attr[0].w */
-//      invert(&exec, 0, 3);
+      /*invert(&exec, 0, 3);*/
    }
 
    /* Interpolate all the remaining attributes.  This will get pushed
     * into the fragment program's responsibilities at some point.
+    * Start at 1 to skip fragment position attribute (computed above).
     */
    for (i = 1; i < quad->nr_attrs; i++) {
-#if 1
-      for (j = 0; j < NUM_CHANNELS; j++)
-	 linterp(&exec, i, j);
-#else
-      switch (quad->interp[i]) {
+      switch (softpipe->interp[i]) {
       case INTERP_CONSTANT:
 	 for (j = 0; j < NUM_CHANNELS; j++)
 	    cinterp(&exec, i, j);
@@ -178,7 +172,6 @@ shade_quad( struct quad_stage *qs, struct quad_header *quad )
 	    pinterp(&exec, i, j);
 	 break;
       }
-#endif
    }
 
 #if 1
@@ -243,6 +236,13 @@ shade_quad( struct quad_stage *qs, struct quad_header *quad )
       memcpy(quad->outputs.color,
              &aoutputs[FRAG_ATTRIB_COL0].xyzw[0].f[0],
              sizeof(quad->outputs.color));
+      if (softpipe->need_z) {
+         /* XXX temporary */
+         quad->outputs.depth[0] = exec.attr[0][2][0];
+         quad->outputs.depth[1] = exec.attr[0][2][1];
+         quad->outputs.depth[2] = exec.attr[0][2][2];
+         quad->outputs.depth[3] = exec.attr[0][2][3];
+      }
    }
 #else
    {
@@ -253,7 +253,7 @@ shade_quad( struct quad_stage *qs, struct quad_header *quad )
 	     exec.attr[attr], 
 	     sizeof(quad->outputs.color));
 
-      if (need_z) {
+      if (softpipe->need_z) {
          quad->outputs.depth[0] = exec.attr[0][2][0];
          quad->outputs.depth[1] = exec.attr[0][2][1];
          quad->outputs.depth[2] = exec.attr[0][2][2];
diff --git a/src/mesa/pipe/softpipe/sp_state_derived.c b/src/mesa/pipe/softpipe/sp_state_derived.c
index a470cc2..84a1ec7 100644
--- a/src/mesa/pipe/softpipe/sp_state_derived.c
+++ b/src/mesa/pipe/softpipe/sp_state_derived.c
@@ -75,6 +75,24 @@ static void calculate_vertex_layout( struct softpipe_context *softpipe )
    GLbitfield attr_mask = 0x0;
    GLuint i;
 
+   /* Need Z if depth test is enabled or the fragment program uses the
+    * fragment position (XYZW).
+    */
+   if (softpipe->depth_test.enabled ||
+       (inputsRead & FRAG_ATTRIB_WPOS))
+      softpipe->need_z = GL_TRUE;
+   else
+      softpipe->need_z = GL_FALSE;
+
+   /* Need W if we do any perspective-corrected interpolation or the
+    * fragment program uses the fragment position.
+    */
+   if (inputsRead & FRAG_ATTRIB_WPOS)
+      softpipe->need_w = GL_TRUE;
+   else
+      softpipe->need_w = GL_FALSE;
+
+
    softpipe->nr_attrs = 0;
    memset(slot_to_vf_attr, 0, sizeof(slot_to_vf_attr));
 
@@ -101,7 +119,8 @@ static void calculate_vertex_layout( struct softpipe_context *softpipe )
 
    for (i = FRAG_ATTRIB_TEX0; i < FRAG_ATTRIB_MAX; i++) {
       if (inputsRead & (1 << i)) {
-	 EMIT_ATTR(frag_to_vf[i], i, INTERP_PERSPECTIVE);
+         EMIT_ATTR(frag_to_vf[i], i, INTERP_PERSPECTIVE);
+         softpipe->need_w = GL_TRUE;
       }
    }
 
-- 
2.7.4