From: Brian Paul <brianp@vmware.com>
Date: Wed, 23 Sep 2009 19:35:03 +0000 (-0600)
Subject: swrast: add lod bias when texture sampling
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=2acd5de22651a3461c0576107c8e8fab1f01469a;p=mesa.git

swrast: add lod bias when texture sampling

Mostly fixes progs/demos/lodbias when MESA_TEX_PROG=1.  But the LOD still
seems off by -1 or so.
May be an issue with the params passed to _swrast_compute_lambda()
---

diff --git a/src/mesa/swrast/s_fragprog.c b/src/mesa/swrast/s_fragprog.c
index 144f78b024a..b326acf3e3c 100644
--- a/src/mesa/swrast/s_fragprog.c
+++ b/src/mesa/swrast/s_fragprog.c
@@ -89,6 +89,8 @@ fetch_texel_lod( GLcontext *ctx, const GLfloat texcoord[4], GLfloat lambda,
  * Fetch a texel with the given partial derivatives to compute a level
  * of detail in the mipmap.
  * Called via machine->FetchTexelDeriv()
+ * \param lodBias  the lod bias which may be specified by a TXB instruction,
+ *                 otherwise zero.
  */
 static void
 fetch_texel_deriv( GLcontext *ctx, const GLfloat texcoord[4],
@@ -96,7 +98,8 @@ fetch_texel_deriv( GLcontext *ctx, const GLfloat texcoord[4],
                    GLfloat lodBias, GLuint unit, GLfloat color[4] )
 {
    SWcontext *swrast = SWRAST_CONTEXT(ctx);
-   const struct gl_texture_object *texObj = ctx->Texture.Unit[unit]._Current;
+   const struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];
+   const struct gl_texture_object *texObj = texUnit->_Current;
 
    if (texObj) {
       const struct gl_texture_image *texImg =
@@ -111,7 +114,9 @@ fetch_texel_deriv( GLcontext *ctx, const GLfloat texcoord[4],
                                       texdx[3], texdy[3], /* dq/dx, dq/dy */
                                       texW, texH,
                                       texcoord[0], texcoord[1], texcoord[3],
-                                      1.0F / texcoord[3]) + lodBias;
+                                      1.0F / texcoord[3]);
+
+      lambda += lodBias + texUnit->LodBias + texObj->LodBias;
 
       lambda = CLAMP(lambda, texObj->MinLod, texObj->MaxLod);