extensions/IGLOO/IGLOO_toggle_color_and_lightXXX.txt

XXX - Not complete yet!!!
XXX - Obsolete; implemented as part of GL_SGIX_igloo_interface

Name

    IGLOO_toggle_color_and_light

Name Strings

    GL_IGLOO_toggle_color_and_lightXXX

    No name should be returned by glGetString, glXQueryExtensionsString, or gluGetString.
    The name string here is used solely in the registry.

Version

    $Date: 1999/04/03 08:40:50 $ $Revision: 1.3 $

Number

    None

	Igloo extensions should be compatible with *ALL* other extensions.
	(i.e. igloo extensions must document their interactions with subsequent
	extensions preceding it, so there is no number).

Dependencies

    None

Overview

       This extension allows for lighting to be disabled and enabled on a per vertex basis.
       This is to emulate the IrisGL behavior of lmcolor(LMC_COLOR);

Issues
       This feature could almost be emulated in software, but it would require an enormous
       number of glMaterial calls.  glMaterial has been shown to be extremely slow
       on RE and EXPRESS. Lit and unlit primitives would both be very slow.

       Should this be a glEnable?  The only reason it isn't an Enable is that
       it should be callable within glBegin and glEnd.	Currently
       we've architected lmcolor with the assumption that it *WILL NOT* be
       called within glBegin/glEnd anyway.

       Should this work in Color Index mode, It is not useful for emulating
       IrisGL since lmcolor has no meaning in color index mode, but
       it could easily be implemented in color index mode and this would
       preserve orthogonality better.

New Procedures and Functions

	void IGLOOToggleColorAndLightXXX(GLboolean switch);


New Tokens

	Accepted by the <pname> parameters of GetBooleanv, GetIntegerv,
	GetFloatv, and GetDoublev:

	TOGGLE_COLOR_AND_LIGHTXXX

	If it is decided that this should be implemented using glEnable, then glIsEnabled
	and glEnable/glDisable should accept this token.

Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation)
    Section 2.12.1 first section.
    "Lighting is turned either on or off using the generic glEnable or glDisable
    commands with the symbol LIGHT." becomes

    "If TOGGLE_COLOR_AND_LIGHTXXX is False, then lighting may be turned on or off using
    the generic glEnable or glDisable.	If TOGGLE_COLOR_AND_LIGHTXXX is True, then lighting
    is on after each 'normal' command, if it is turned on with glEnable.
    lighting is off after each 'color' command.
    Lighting is always off if it
    has been turned off with glDisable."

    /* XXX I'm trying to make it clear that the ordering of the color and normal
    commands doesn't persist from befor lighting is enabled, or from befor TOGGLE_COLOR_AND_LIGHTXXX
    is set to TRUE */

    Section 2.12.3 (ColorMaterial)
    End of section.
    "Executing a glVertex when glColorMaterial is Enabled,
    and TOGGLE_COLOR_AND_LIGHTXXX is TRUE results in indeterminate behavior."

    Section 2.12.4 (Lighting State)
    First sentence
    The state required for lighting consists of all of the lighting parameters (front
    and back material parameters, lighting model parameters, and at least 8 sets of light
    parameters), a bit indicating whether a back color distinct from the front color should
    be computed, at least 8 bits to indicate which lights are enabled, a five valued
    variable indicating the current ColorMaterial mode, a bit indicating whether or not
    COLOR_MATERIAL is enabled, *** A bit to indicate whether or
    not TOGGLE_COLOR_AND_LIGHTXXX is TRUE,*** and a single bit to indicate whether
    lighting is enabled or disabled.



Additions to Chapter 3 of the 1.0 Specification (Rasterization)

    None

Additions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations
and the Frame Buffer)
    None

Additions to Chapter 5 of the 1.0 Specification (Special Functions)


*    This command *SHOULD be display listable, hence nothing about display lists
*    is added here.

     Section 5.1 (Evaluators).
     After paragraph 12 (which starts with "Finally, if either MAP2_VERTEX_3 or MAP2_VERTEX_4
     is enabled, then the normal to the surface is computed analytically."

     This paragraph should be followed by
     "If AUTO_NORMAL is enabled, or if MAP[12]_NORMAL is defined and enabled at the same
     time that MAP[12]_COLOR is defined and enabled. Then the normal is computed after
     the color so that lighting may be enabled if TOGGLE_COLOR_AND_LIGHTXXX is TRUE."

Additions to Chapter 6 of the 1.0 Specification (State and State Requests)


Additions to the GLX Specification

    This extensions does *NOT* need to be recognized by glX.

GLX Protocol

    This extensions should *NOT* be recognized by glX.

Dependencies on SGI_extension_name

    None

Errors
*	Calling glNormal or glColor when TOGGLECOLORANDLIGHTXXX is TRUE and
*	ColorMaterial is Enabled results in indeterminate behavior.

New State

*	It is unknown whether this is client state since it is not useful on the
*	client side, but glX needn't recognize it.
								Initial
    Get Value				Get Command	Type	Value	Attrib
    ---------				-----------	----	------- ------
    TOGGLE_COLOR_AND_LIGHTXXX		glGet		Boolean  FALSE	lighting

    (I've chosen not to make this a glEnable,  so it isn't part of the Enable Attribute
    This is perhaps controversial)

New Implementation Dependent State

*	Description of all implementation dependent state in table format.

    None