Update and improve documentation

[libs/gl.git] / source / core / texture.h

diff --git a/source/core/texture.h b/source/core/texture.h
index c593c0ad5236657ac4f08b45ded75f8c3a144f4b..13ff5bc9f73095094a0800cd1efbd5aaa3a4246a 100644 (file)
--- a/source/core/texture.h
+++ b/source/core/texture.h
@@ -12,13 +12,20 @@ namespace Msp {
 namespace GL {
 
 /**
-Base class for textures.  This class only defines operations common for all
-texture types and is not instantiable.  For specifying images for textures,
-see one of the dimensioned texture classes.
+Base class for textures.  Most operations are defined in subclasses.
 
-A texture can consinst of a stack of images, called a mipmap.  The dimensions
-of each mipmap level are half that of the previous level.  The mipmap stack
-can be used for texture minification; see the Sampler class for details.
+Memory must be allocated for the texture by calling storage().  Each subclass
+provides this function with parameters appropriate to that type of texture.
+Contents can then be modified using the image() and sub_image() functions
+provided by subclasses.
+
+Most types of textures can consist of a pyramid of images, called a mipmap.
+The dimensions of each mipmap level are half that of the previous level.
+
+Textures can be used as either a data source or target for draw commands.  To
+read from a texture in a shader, it must be paired with a Sampler to determine
+how the texels are accessed.  To draw into a texture, it must be attached to a
+Framebuffer.
 */
 class Texture: public TextureBackend, public Resource
 {
@@ -86,12 +93,13 @@ public:
 
        using TextureBackend::generate_mipmap;
 
-       /// Loads a Graphics::Image from a file and uploads it to the texture.
+       /** Loads an image into the texture from a file. */
        virtual void load_image(const std::string &, unsigned = 0);
 
-       /** Uploads an image to the texture.  If storage has not been defined, it
-       will be set to match the image.  Otherwise the image must be compatible
-       with the defined storage.  Semantics depend on the type of texture.  */
+       /** Sets the texture's contents from an image.  If storage has not been
+       allocated yet, it will be set to match the image.  Otherwise the image must
+       be compatible with the existing storage.  Subclasses may impose restrictions
+       on the image's dimensions. */
        virtual void image(const Graphics::Image &, unsigned = 0) = 0;
 
        virtual std::size_t get_data_size() const { return 0; }