From 04d324531fc70c881d80774e933dc6c5feabe531 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Thu, 6 Aug 2009 14:46:32 -0400
Subject: [PATCH] Cleanup program binding at link time.

Only bind program at link time if forced to, only do it once, and only reset
 the binding back to the original state at the end, if necessary.
---
 mojoshader_opengl.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/mojoshader_opengl.c b/mojoshader_opengl.c
index 0523cb6b..94d7f6d7 100644
--- a/mojoshader_opengl.c
+++ b/mojoshader_opengl.c
@@ -1162,7 +1162,7 @@ static void fill_constant_array(GLfloat *f, const int base, const int size,
 
 
 static void lookup_uniforms(MOJOSHADER_glProgram *program,
-                            MOJOSHADER_glShader *shader)
+                            MOJOSHADER_glShader *shader, int *bound)
 {
     const MOJOSHADER_parseData *pd = shader->parseData;
     const MOJOSHADER_shaderType shader_type = pd->shader_type;
@@ -1183,9 +1183,12 @@ static void lookup_uniforms(MOJOSHADER_glProgram *program,
                     const int size = u->array_count;
                     GLfloat *f = (GLfloat *) alloca(sizeof (GLfloat)*(size*4));
                     fill_constant_array(f, base, size, pd);
-                    ctx->profileUseProgramObject(program);
+                    if (!(*bound))
+                    {
+                        ctx->profileUseProgramObject(program);
+                        *bound = 1;
+                    } // if
                     ctx->profileUniform4fv(pd, loc, size, f);
-                    ctx->profileUseProgramObject(ctx->bound_program);
                 } // if
             } // if
 
@@ -1203,7 +1206,7 @@ static void lookup_uniforms(MOJOSHADER_glProgram *program,
 
 
 static void lookup_samplers(MOJOSHADER_glProgram *program,
-                            MOJOSHADER_glShader *shader)
+                            MOJOSHADER_glShader *shader, int *bound)
 {
     const MOJOSHADER_parseData *pd = shader->parseData;
     const MOJOSHADER_sampler *s = pd->samplers;
@@ -1215,7 +1218,11 @@ static void lookup_samplers(MOJOSHADER_glProgram *program,
     // Link up the Samplers. These never change after link time, since they
     //  are meant to be constant texture unit ids and not textures.
 
-    ctx->profileUseProgramObject(program);
+    if (!(*bound))
+    {
+        ctx->profileUseProgramObject(program);
+        *bound = 1;
+    } // if
 
     for (i = 0; i < pd->sampler_count; i++)
     {
@@ -1223,8 +1230,6 @@ static void lookup_samplers(MOJOSHADER_glProgram *program,
         if (loc != -1)  // maybe the Sampler was optimized out?
             ctx->profileSetSampler(loc, s[i].index);
     } // for
-
-    ctx->profileUseProgramObject(ctx->bound_program);
 } // lookup_samplers
 
 
@@ -1284,6 +1289,8 @@ static int build_constants_lists(MOJOSHADER_glProgram *program)
 MOJOSHADER_glProgram *MOJOSHADER_glLinkProgram(MOJOSHADER_glShader *vshader,
                                                MOJOSHADER_glShader *pshader)
 {
+    int bound = 0;
+
     if ((vshader == NULL) && (pshader == NULL))
         return NULL;
 
@@ -1329,21 +1336,24 @@ MOJOSHADER_glProgram *MOJOSHADER_glLinkProgram(MOJOSHADER_glShader *vshader,
             lookup_attributes(retval);
         } // if
 
-        lookup_uniforms(retval, vshader);
-        lookup_samplers(retval, vshader);
+        lookup_uniforms(retval, vshader, &bound);
+        lookup_samplers(retval, vshader, &bound);
         vshader->refcount++;
     } // if
 
     if (pshader != NULL)
     {
-        lookup_uniforms(retval, pshader);
-        lookup_samplers(retval, pshader);
+        lookup_uniforms(retval, pshader, &bound);
+        lookup_samplers(retval, pshader, &bound);
         pshader->refcount++;
     } // if
 
     if (!build_constants_lists(retval))
         goto link_program_fail;
 
+    if (bound)  // reset the old binding.
+        ctx->profileUseProgramObject(ctx->bound_program);
+
     return retval;
 
 link_program_fail:
@@ -1360,6 +1370,9 @@ MOJOSHADER_glProgram *MOJOSHADER_glLinkProgram(MOJOSHADER_glShader *vshader,
     if (program != 0)
         ctx->profileDeleteProgram(program);
 
+    if (bound)
+        ctx->profileUseProgramObject(ctx->bound_program);
+
     return NULL;
 } // MOJOSHADER_glLinkProgram