main: Added entry point for BindTextureUnit.

The following preparations were made in texstate.c and texstate.h to
better facilitate the BindTextureUnit function:

Dylan Noblesmith:
mesa: add _mesa_get_tex_unit()
mesa: factor out _mesa_max_tex_unit()
This is about to appear in a lot more places, so
reduce boilerplate copy paste.
add _mesa_get_tex_unit_err() checking getter function
Reduce boilerplate across files.

Laura Ekstrand:
Made note of why BindTextureUnit should throw GL_INVALID_OPERATION if the unit is out of range.
Added assert(unit > 0) to _mesa_get_tex_unit.

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>

1 files changed, 37 insertions, 2 deletions

diff --git a/src/mesa/main/texstate.h b/src/mesa/main/texstate.h
index 5cd1684..2514d10 100644
--- a/src/mesa/main/texstate.h
+++ b/src/mesa/main/texstate.h
@@ -33,9 +33,19 @@
 
 
 #include "compiler.h"
+#include "enums.h"
+#include "macros.h"
 #include "mtypes.h"
 
 
+static inline struct gl_texture_unit *
+_mesa_get_tex_unit(struct gl_context *ctx, GLuint unit)
+{
+   ASSERT(unit >= 0);
+   ASSERT(unit < Elements(ctx->Texture.Unit));
+   return &(ctx->Texture.Unit[unit]);
+}
+
 /**
  * Return pointer to current texture unit.
  * This the texture unit set by glActiveTexture(), not glClientActiveTexture().
@@ -43,8 +53,33 @@
 static inline struct gl_texture_unit *
 _mesa_get_current_tex_unit(struct gl_context *ctx)
 {
-   ASSERT(ctx->Texture.CurrentUnit < Elements(ctx->Texture.Unit));
-   return &(ctx->Texture.Unit[ctx->Texture.CurrentUnit]);
+   return _mesa_get_tex_unit(ctx, ctx->Texture.CurrentUnit);
+}
+
+static inline GLuint
+_mesa_max_tex_unit(struct gl_context *ctx)
+{
+   /* See OpenGL spec for glActiveTexture: */
+   return MAX2(ctx->Const.MaxCombinedTextureImageUnits,
+               ctx->Const.MaxTextureCoordUnits);
+}
+
+static inline struct gl_texture_unit *
+_mesa_get_tex_unit_err(struct gl_context *ctx, GLuint unit, const char *func)
+{
+   if (unit < _mesa_max_tex_unit(ctx))
+      return _mesa_get_tex_unit(ctx, unit);
+
+   /* Note: This error is a precedent set by glBindTextures. From the GL 4.5
+    * specification (30.10.2014) Section 8.1 ("Texture Objects"):
+    *
+    *    "An INVALID_OPERATION error is generated if first + count is greater
+    *     than the number of texture image units supported by the
+    *     implementation."
+    */
+   _mesa_error(ctx, GL_INVALID_OPERATION, "%s(unit=%s)", func,
+               _mesa_lookup_enum_by_nr(GL_TEXTURE0+unit));
+   return NULL;
 }