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 <[email protected]>

5 files changed, 150 insertions, 5 deletions

diff --git a/src/mesa/main/tests/dispatch_sanity.cpp b/src/mesa/main/tests/dispatch_sanity.cpp
index c9decb7af8b..0ef48c9b299 100644
--- a/src/mesa/main/tests/dispatch_sanity.cpp
+++ b/src/mesa/main/tests/dispatch_sanity.cpp
@@ -962,6 +962,7 @@ const struct function gl_core_functions_possible[] = {
    { "glTextureSubImage1D", 45, -1 },
    { "glTextureSubImage2D", 45, -1 },
    { "glTextureSubImage3D", 45, -1 },
+   { "glBindTextureUnit", 45, -1 },
 
    { NULL, 0, -1 }
 };
diff --git a/src/mesa/main/texobj.c b/src/mesa/main/texobj.c
index 416b7df20c9..e9f5fbfbf45 100644
--- a/src/mesa/main/texobj.c
+++ b/src/mesa/main/texobj.c
@@ -502,6 +502,9 @@ _mesa_reference_texobj_(struct gl_texture_object **ptr,
       mtx_unlock(&oldTex->Mutex);
 
       if (deleteFlag) {
+         /* Passing in the context drastically changes the driver code for
+          * framebuffer deletion.
+          */
          GET_CURRENT_CONTEXT(ctx);
          if (ctx)
             ctx->Driver.DeleteTexture(ctx, oldTex);
@@ -1598,6 +1601,107 @@ _mesa_BindTexture( GLenum target, GLuint texName )
       ctx->Driver.BindTexture(ctx, ctx->Texture.CurrentUnit, target, newTexObj);
 }
 
+/**
+ * Do the actual binding to a numbered texture unit.
+ * The refcount on the previously bound
+ * texture object will be decremented.  It'll be deleted if the
+ * count hits zero.
+ */
+void
+_mesa_bind_texture_unit(struct gl_context *ctx,
+                        GLuint unit,
+                        struct gl_texture_object *texObj)
+{
+   struct gl_texture_unit *texUnit;
+
+   /* Get the texture unit (this is an array look-up) */
+   texUnit = _mesa_get_tex_unit_err(ctx, unit, "glBindTextureUnit");
+   if (!texUnit)
+      return;
+
+   /* Check if this texture is only used by this context and is already bound.
+    * If so, just return.
+    */
+   {
+      bool early_out;
+      mtx_lock(&ctx->Shared->Mutex);
+      early_out = ((ctx->Shared->RefCount == 1)
+                   && (texObj == texUnit->CurrentTex[texObj->TargetIndex]));
+      mtx_unlock(&ctx->Shared->Mutex);
+      if (early_out) {
+         return;
+      }
+   }
+
+   /* flush before changing binding */
+   FLUSH_VERTICES(ctx, _NEW_TEXTURE);
+
+   _mesa_reference_texobj(&texUnit->CurrentTex[texObj->TargetIndex],
+                          texObj);
+   ASSERT(texUnit->CurrentTex[texObj->TargetIndex]);
+   ctx->Texture.NumCurrentTexUsed = MAX2(ctx->Texture.NumCurrentTexUsed,
+                                         unit + 1);
+   texUnit->_BoundTextures |= (1 << texObj->TargetIndex);
+
+
+   /* Pass BindTexture call to device driver */
+   if (ctx->Driver.BindTexture) {
+      ctx->Driver.BindTexture(ctx, unit, texObj->Target, texObj);
+   }
+}
+
+/**
+ * Bind a named texture to the specified texture unit.
+ *
+ * \param unit texture unit.
+ * \param texture texture name.
+ *
+ * \sa glBindTexture().
+ *
+ * If the named texture is 0, this will reset each target for the specified
+ * texture unit to its default texture.
+ * If the named texture is not 0 or a recognized texture name, this throws
+ * GL_INVALID_OPERATION.
+ */
+void GLAPIENTRY
+_mesa_BindTextureUnit(GLuint unit, GLuint texture)
+{
+   GET_CURRENT_CONTEXT(ctx);
+   struct gl_texture_object *texObj;
+
+   if (MESA_VERBOSE & (VERBOSE_API|VERBOSE_TEXTURE))
+      _mesa_debug(ctx, "glBindTextureUnit %s %d\n",
+                  _mesa_lookup_enum_by_nr(GL_TEXTURE0+unit), (GLint) texture);
+
+   /* Section 8.1 (Texture Objects) of the OpenGL 4.5 core profile spec
+    * (20141030) says:
+    *    "When texture is zero, each of the targets enumerated at the
+    *    beginning of this section is reset to its default texture for the
+    *    corresponding texture image unit."
+    */
+   if (texture == 0) {
+      unbind_textures_from_unit(ctx, unit);
+      return;
+   }
+
+   /* Get the non-default texture object */
+   texObj = _mesa_lookup_texture(ctx, texture);
+
+   /* Error checking */
+   if (!texObj) {
+      _mesa_error(ctx, GL_INVALID_OPERATION,
+         "glBindTextureUnit(non-gen name)");
+      return;
+   }
+   if (texObj->Target == 0) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glBindTextureUnit(target)");
+      return;
+   }
+   assert(valid_texture_object(texObj));
+
+   _mesa_bind_texture_unit(ctx, unit, texObj);
+}
+
 
 void GLAPIENTRY
 _mesa_BindTextures(GLuint first, GLsizei count, const GLuint *textures)
diff --git a/src/mesa/main/texobj.h b/src/mesa/main/texobj.h
index e7aabbe8912..723b2773b62 100644
--- a/src/mesa/main/texobj.h
+++ b/src/mesa/main/texobj.h
@@ -198,6 +198,11 @@ _mesa_unlock_context_textures( struct gl_context *ctx );
 extern void
 _mesa_lock_context_textures( struct gl_context *ctx );
 
+extern void
+_mesa_bind_texture_unit(struct gl_context *ctx,
+                        GLuint unit,
+                        struct gl_texture_object *texObj);
+
 /*@}*/
 
 /**
@@ -218,6 +223,8 @@ _mesa_DeleteTextures( GLsizei n, const GLuint *textures );
 extern void GLAPIENTRY
 _mesa_BindTexture( GLenum target, GLuint texture );
 
+extern void GLAPIENTRY
+_mesa_BindTextureUnit(GLuint unit, GLuint texture);
 
 extern void GLAPIENTRY
 _mesa_BindTextures( GLuint first, GLsizei count, const GLuint *textures );
diff --git a/src/mesa/main/texstate.c b/src/mesa/main/texstate.c
index 36eefa6e654..66fd7183e3b 100644
--- a/src/mesa/main/texstate.c
+++ b/src/mesa/main/texstate.c
@@ -290,9 +290,7 @@ _mesa_ActiveTexture(GLenum texture)
    GLuint k;
    GET_CURRENT_CONTEXT(ctx);
 
-   /* See OpenGL spec for glActiveTexture: */
-   k = MAX2(ctx->Const.MaxCombinedTextureImageUnits,
-            ctx->Const.MaxTextureCoordUnits);
+   k = _mesa_max_tex_unit(ctx);
 
    ASSERT(k <= Elements(ctx->Texture.Unit));
 
diff --git a/src/mesa/main/texstate.h b/src/mesa/main/texstate.h
index 5cd1684f225..2514d104b62 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;
 }