mesa: add a UniformBooleanTrue option

Drivers supporting native integers set UniformBooleanTrue to the integer value
that should be used for true when uploading uniform booleans.  This is ~0 for
Gallium and 1 for i965.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/mesa/drivers/dri/i965/brw_context.c

@@ -253,8 +253,10 @@ GLboolean brwCreateContext( int api,
    /* If we're using the new shader backend, we require integer uniforms
     * stored as actual integers.
     */
-   if (brw->new_vs_backend)
+   if (brw->new_vs_backend) {
       ctx->Const.NativeIntegers = true;
+      ctx->Const.UniformBooleanTrue = 1;
+   }
 
    return GL_TRUE;
 }

src/mesa/main/mtypes.h

@@ -2722,6 +2722,12 @@ struct gl_constants
     */
    GLboolean NativeIntegers;
 
+   /**
+    * If the driver supports real 32-bit integers, what integer value should be
+    * used for boolean true in uniform uploads?  (Usually 1 or ~0.)
+    */
+   GLuint UniformBooleanTrue;
+
    /** Which texture units support GL_ATI_envmap_bumpmap as targets */
    GLbitfield SupportedBumpUnits;
 

src/mesa/main/uniforms.c

@@ -802,7 +802,10 @@ set_program_uniform(struct gl_context *ctx, struct gl_program *program,
                else
                   uniformVal[i].b = uniformVal[i].u ? 1 : 0;
                
-               if (!ctx->Const.NativeIntegers)
+               if (ctx->Const.NativeIntegers)
+                  uniformVal[i].u =
+                        uniformVal[i].b ? ctx->Const.UniformBooleanTrue : 0;
+               else
                   uniformVal[i].f = uniformVal[i].b ? 1.0f : 0.0f;
             }
          }

src/mesa/state_tracker/st_extensions.c

@@ -207,6 +207,7 @@ void st_init_limits(struct st_context *st)
       c->MaxProgramTexelOffset = screen->get_param(screen, PIPE_CAP_MAX_TEXEL_OFFSET);
 
       c->GLSLVersion = 120;
+      c->UniformBooleanTrue = ~0;
    }
 }