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Name
SGIX_shadow_ambient
Name Strings
GL_SGIX_shadow_ambient
Version
$Date: 1997/02/26 03:36:32 $ $Revision: 1.3 $
Number
90
Dependencies
None.
Overview
This extension allows a value other than 0.0 to be returned by the
SGIX_shadow operation in the case when the shadow test passes.
With this extension any floating point value in the range [0.0,
1.0] can be returned as the texture value when an object is in
shadow. This allows the (untextured) ambient lighting and direct
shadowed lighting from a single light source to be computed in a
single pass.
New Procedures and Functions
None
New Tokens
Accepted by the <pname> parameter of TexParameterf, TexParameteri,
TexParameterfv, TexParameteriv, GetTexParameterfv, and
GetTexParameteriv:
SHADOW_AMBIENT_SGIX 0x80BF
Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation)
None
Additions to Chapter 3 of the 1.0 Specification (Rasterization)
GL Specification Table 3.8 is updated as follows:
Name Type Legal Values
---- ---- ------------
TEXTURE_WRAP_S integer CLAMP, REPEAT
TEXTURE_WRAP_T integer CLAMP, REPEAT
TEXTURE_WRAP_R_EXT integer CLAMP, REPEAT
TEXTURE_MIN_FILTER integer NEAREST, LINEAR,
NEAREST_MIPMAP_NEAREST,
NEAREST_MIPMAP_LINEAR,
LINEAR_MIPMAP_NEAREST,
LINEAR_MIPMAP_LINEAR,
FILTER4_SGIS,
LINEAR_CLIPMAP_LINEAR_SGIX
TEXTURE_MAG_FILTER integer NEAREST, LINEAR,
FILTER4_SGIS,
LINEAR_DETAIL_SGIS,
LINEAR_DETAIL_ALPHA_SGIS,
LINEAR_DETAIL_COLOR_SGIS,
LINEAR_SHARPEN_SGIS,
LINEAR_SHARPEN_ALPHA_SGIS,
LINEAR_SHARPEN_COLOR_SGIS,
TEXTURE_BORDER_COLOR 4 floats any 4 values in [0,1]
DETAIL_TEXTURE_LEVEL_SGIS integer any non-negative integer
DETAIL_TEXTURE_MODE_SGIS integer ADD, MODULATE
TEXTURE_MIN_LOD_SGIS float any value
TEXTURE_MAX_LOD_SGIS float any value
TEXTURE_BASE_LEVEL_SGIS integer any non-negative integer
TEXTURE_MAX_LEVEL_SGIS integer any non-negative integer
GENERATE_MIPMAP_SGIS boolean TRUE or FALSE
TEXTURE_CLIPMAP_OFFSET_SGIX 2 floats any 2 values
SHADOW_AMBIENT_SGIX float any value
Table 3.8: Texture parameters and their values.
Notes:
* A new texture parameter is defined which changes the sampled
texture value when SGIX_shadow is used, and a pixel is determined
to be in shadow. In this case, the value of the
SHADOW_AMBIENT_SGIX parameter is returned, instead of 0.0 . When
SHADOW_AMBIENT_SGIX is set, the <param> value is clamped to the
range [0.0, 1.0].
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)
None
Additions to Chapter 6 of the 1.0 Specification (State and State Requests)
The shadow ambient value is queried by calling GetTexParameterfv
with <pname> set to SHADOW_AMBIENT_SGIX.
Additions to the GLX Specification
None
Errors
None
New State
Get Value Get Command Type Initial Value Attribute
--------- ----------- ---- ------------- ---------
SHADOW_AMBIENT_SGIX GetTexParameter[if]v F 0.0 texture
New Implementation Dependent State
None