[Mesa-dev] [PATCH v2] mesa: Define helper function to get the number of texture layers.

[Francisco Jerez]

And to check if it can have layers at all.  This will be used by the
implementation of ARB_shader_image_load_store.

v2: Fix constness of texobj argument, use assert and return reasonable
    default rather than calling unreachable() in default switch case.
---
 src/mesa/main/teximage.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/mesa/main/teximage.h |  6 ++++
 2 files changed, 93 insertions(+)

diff --git a/src/mesa/main/teximage.c b/src/mesa/main/teximage.c
index 7ec3e20..cf8def1 100644
--- a/src/mesa/main/teximage.c
+++ b/src/mesa/main/teximage.c
@@ -1089,6 +1089,93 @@ _mesa_get_texture_dimensions(GLenum target)
 
 
 /**
+ * Check if a texture target can have more than one layer.
+ */
+GLboolean
+_mesa_tex_target_is_layered(GLenum target)
+{
+   switch (target) {
+   case GL_TEXTURE_1D:
+   case GL_PROXY_TEXTURE_1D:
+   case GL_TEXTURE_2D:
+   case GL_PROXY_TEXTURE_2D:
+   case GL_TEXTURE_RECTANGLE:
+   case GL_PROXY_TEXTURE_RECTANGLE:
+   case GL_TEXTURE_2D_MULTISAMPLE:
+   case GL_PROXY_TEXTURE_2D_MULTISAMPLE:
+   case GL_TEXTURE_BUFFER:
+   case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
+   case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
+   case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
+   case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
+   case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
+   case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
+   case GL_TEXTURE_EXTERNAL_OES:
+      return GL_FALSE;
+
+   case GL_TEXTURE_3D:
+   case GL_PROXY_TEXTURE_3D:
+   case GL_TEXTURE_CUBE_MAP:
+   case GL_PROXY_TEXTURE_CUBE_MAP:
+   case GL_TEXTURE_1D_ARRAY:
+   case GL_PROXY_TEXTURE_1D_ARRAY:
+   case GL_TEXTURE_2D_ARRAY:
+   case GL_PROXY_TEXTURE_2D_ARRAY:
+   case GL_TEXTURE_CUBE_MAP_ARRAY:
+   case GL_PROXY_TEXTURE_CUBE_MAP_ARRAY:
+   case GL_TEXTURE_2D_MULTISAMPLE_ARRAY:
+   case GL_PROXY_TEXTURE_2D_MULTISAMPLE_ARRAY:
+      return GL_TRUE;
+
+   default:
+      assert(!"Invalid texture target.");
+      return GL_FALSE;
+   }
+}
+
+
+/**
+ * Return the number of layers present in the given level of an array,
+ * cubemap or 3D texture.  If the texture is not layered return zero.
+ */
+GLuint
+_mesa_get_texture_layers(const struct gl_texture_object *texObj, GLint level)
+{
+   assert(level >= 0 && level < MAX_TEXTURE_LEVELS);
+
+   switch (texObj->Target) {
+   case GL_TEXTURE_1D:
+   case GL_TEXTURE_2D:
+   case GL_TEXTURE_RECTANGLE:
+   case GL_TEXTURE_2D_MULTISAMPLE:
+   case GL_TEXTURE_BUFFER:
+   case GL_TEXTURE_EXTERNAL_OES:
+      return 0;
+
+   case GL_TEXTURE_CUBE_MAP:
+      return 6;
+
+   case GL_TEXTURE_1D_ARRAY: {
+      struct gl_texture_image *img = texObj->Image[0][level];
+      return img ? img->Height : 0;
+   }
+
+   case GL_TEXTURE_3D:
+   case GL_TEXTURE_2D_ARRAY:
+   case GL_TEXTURE_CUBE_MAP_ARRAY:
+   case GL_TEXTURE_2D_MULTISAMPLE_ARRAY: {
+      struct gl_texture_image *img = texObj->Image[0][level];
+      return img ? img->Depth : 0;
+   }
+
+   default:
+      assert(!"Invalid texture target.");
+      return 0;
+   }
+}
+
+
+/**
  * Return the maximum number of mipmap levels for the given target
  * and the dimensions.
  * The dimensions are expected not to include the border.
diff --git a/src/mesa/main/teximage.h b/src/mesa/main/teximage.h
index 792383d..3e7d821 100644
--- a/src/mesa/main/teximage.h
+++ b/src/mesa/main/teximage.h
@@ -138,6 +138,12 @@ _mesa_tex_target_to_face(GLenum target);
 extern GLint
 _mesa_get_texture_dimensions(GLenum target);
 
+extern GLboolean
+_mesa_tex_target_is_layered(GLenum target);
+
+extern GLuint
+_mesa_get_texture_layers(const struct gl_texture_object *texObj, GLint level);
+
 extern GLsizei
 _mesa_get_tex_max_num_levels(GLenum target, GLsizei width, GLsizei height,
                              GLsizei depth);
-- 
1.8.5.1