WGL_EXT_depth_float

Name

    EXT_depth_float

Name Strings

    WGL_EXT_depth_float

Version

    Date: 1/27/1999  Version 1.4

Number

    177

Dependencies

    WGL_EXT_extensions_string is required.
    WGL_EXT_pixel_format is required.

Overview

    For perspective scenes, the density of objects (vertices) increases
    as the distance from the eye increases.  For a linear depth buffer,
    this means that objects (vertices) are sparse for a large portion of
    the depth range and are dense for a small portion of the depth buffer.

    This behavior is obvious if you consider standing in a boat looking
    at the shore.  The near objects include only the boat while the far
    objects include the entire shoreline which may include an entire city.

    A non-linear (floating-point) depth buffer helps this problem.  If
    the near clipping plane is set to 1.0, and the far clipping plane is
    set to 0.0, a much greater resolution of objects can occur.

New Procedures and Functions

    None

New Tokens

    Accepted by the <attribute> parameter of wglGetPixelFormatAttribivEXT,
    wglGetPixelFormatAttribfvEXT, and wglChoosePixelFormatExEXT:

      WGL_DEPTH_FLOAT_EXT                  0x2040

Additions to Chapter 2 of the 1.2 Specification (OpenGL Operation)

    Each of n and f are clamped to lie within [0,1], as are all arguments
    of type clampd or clampf.  zw is taken to be represented in either
    fixed-point or floating-point depending on the attributes of the
    window.

    If the depth buffer is a fixed-point format, then zw is taken to be
    represented in fixed-point with at least as many bits as there are
    in the depth buffer of the framebuffer.  We assume that the fixed-point
    representation used represents each value k/(2^m - 1), where k is in
    the set {0,1,...,2^m - 1}, as k (e.g. 1.0 is represented in the binary
    as a string of all ones).

    If the depth buffer is a floating-point format, then zw is taken to be
    represented in floating-point with at least as many bits as there are
    in the depth buffer of the framebuffer.  The floating-point
    representation is implementation dependent.

Additions to Chapter 3 of the 1.2 Specification (Rasterization)

    None

Additions to Chapter 4 of the 1.2 Specification (Per-Fragment Operations and the Framebuffer)

    None

Additions to Chapter 5 of the 1.2 Specification (Special Functions)

    None

Additions to Chapter 6 of the 1.2 Specification (State and State Requests)

    None

Additions to the WGL Specification

    None

Errors

    None

New State

    None

New Implementation Dependent State

    None

Implementation Support

   List of OpenGL implementations supporting the WGL_EXT_depth_float extension

Original File

   Original text file for the WGL_EXT_depth_float extension