Comment updates for texture and framebuffer classes.

[libs/gl.git] / source / texture2d.h

diff --git a/source/texture2d.h b/source/texture2d.h
index 5f4a7f9293e49f90781dbeaa50322cd6cc90747c..ff4d35b64b24685661f842b6f652604b0d4220a4 100644 (file)
--- a/source/texture2d.h
+++ b/source/texture2d.h
@@ -11,7 +11,9 @@ namespace Msp {
 namespace GL {
 
 /**
-Two-dimensional texture class.  This is the most common type of texture.
+Two-dimensional texture.  Consists of an array of texels in the shape of a
+rectangle.  Texture coordinate have a principal range of [0, 1].  This is the
+most common type of texture.
 */
 class Texture2D: public Texture
 {
@@ -36,31 +38,28 @@ private:
 public:
        Texture2D();
 
-       /**
-       Defines the texture storage.  This function may only be successfully called
-       once.
-       */
+       /** Defines storage structure for the texture.  Must be called before an
+       image can be uploaded.  Once storage is defined, it can't be changed. */
        void storage(PixelFormat fmt, unsigned wd, unsigned ht);
 
-       /** Allocates texture storage.  If storage has already been allocated, this
-       function does nothing. */
+       /** Allocates storage for the texture.  The contents are initially
+       undefined.  If storage has already been allocated, does nothing. */
        void allocate(unsigned level);
        
-       /** Uploads an image to the texture.  storage() must have been called prior to
-       this, and the image must have dimensions conforming to the specified
-       storage.  For level>0, mipmapping rules apply to the image dimensions. */
+       /** Uploads an image to the texture.  Storage must be defined beforehand.
+       The image data must have dimensions and format compatible with the defined
+       storage. */
        void image(unsigned level, PixelFormat fmt, DataType type, const void *data);
 
-       /**
-       Uploads a sub-image into the texture.  Unlike full image upload, there are
-       no constraints on the size of the sub-image.
-       */
-       void sub_image(unsigned level, int x, int y, unsigned wd, unsigned ht, PixelFormat fmt, DataType type, const void *data);
+       /** Updates a rectangular region of the texture.  Storage must be defined
+       and allocated beforehand.  The update region must be fully inside the
+       texture. */
+       void sub_image(unsigned level, int x, int y, unsigned wd, unsigned ht,
+               PixelFormat fmt, DataType type, const void *data);
 
-       /**
-       Loads an image from a file and uploads it to the texture.  If storage() has
-       not been called, the storage format will be set to match the loaded image.
-       */
+       /** Loads an image from a file and uploads it to the texture.  If storage
+       has not been defined, it will be set to match the loaded image.  Otherwise
+       the image must be compatible with the defined storage. */
        void load_image(const std::string &fn);
 
        unsigned get_width() const  { return width; }