glSpriteParameterSGIX(3G)      OpenGL Reference	     glSpriteParameterSGIX(3G)

NAME    [Toc]    [Back]

     glSpriteParameterfSGIX, glSpriteParameteriSGIX, glSpriteParameterfvSGIX,
     glSpriteParameterivSGIX - set sprite parameters

C SPECIFICATION    [Toc]    [Back]

     void glSpriteParameterfSGIX( GLenum pname,
				  GLfloat param	)
     void glSpriteParameteriSGIX( GLenum pname,
				  GLint	param )

PARAMETERS    [Toc]    [Back]

     pname   The parameter to be set. Must be GL_SPRITE_MODE_SGIX.

     param   The parameter value.  Must	be one of GL_SPRITE_AXIAL_SGIX or
	     GL_SPRITE_OBJECT_ALIGNED_SGIX or GL_SPRITE_EYE_ALIGNED_SGIX.

C SPECIFICATION    [Toc]    [Back]

     void glSpriteParameterfvSGIX( GLenum pname,
				   const GLfloat *params )
     void glSpriteParameterivSGIX( GLenum pname,
				   const GLint *params )

PARAMETERS    [Toc]    [Back]

     pname
	  The parameter	to be set. Must	be one of GL_SPRITE_MODE_SGIX or
	  GL_SPRITE_AXIS_SGIX or GL_SPRITE_TRANSLATION_SGIX.

     params
	  Must be a pointer to a scalar	(GL_SPRITE_MODE_SGIX) or to a threevalued
 vector	(GL_SPRITE_AXIS_SGIX or	GL_SPRITE_TRANSLATION_SGIX for
	  x, y,	z, respectively).

DESCRIPTION    [Toc]    [Back]

     glSpriteParameterSGIX is part of the GL_SGIX_sprite extension.  This
     extension provides	support	for geometry that rotates to face the eye, in
     the manner	of Iris	Performer billboards.  This is most useful for fast
     approximate rendering of objects that have	rough spherical	or cylindrical
     symmetry, such as trees, smoke, and clouds, where the objects are modeled
     as	simple geometry	covered	by a complex partially-transparent texture
     map.

     Sprite geometry is	modelled in a canonical	frame in which +Z is the up
     vector, and -Y is the front vector	which is rotated to point to the eye.

     Rendering sprite geometry requires	applying a transformation to
     primitives	before applying	the current modelview matrix.  This
     transformation is based on	the current modelview matrix, the sprite



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glSpriteParameterSGIX(3G)      OpenGL Reference	     glSpriteParameterSGIX(3G)



     rendering mode, and the constraints on sprite motion.

     glSpriteParameterSGIX sets	the value of a sprite parameter.  pname
     specifies the parameter to	be changed.

     When pname	is GL_SPRITE_MODE_SGIX,	param specifies	the sprite rendering
     mode.  param must be one of the following values:

     GL_SPRITE_AXIAL_SGIX    [Toc]    [Back]
	       The front of the	object is rotated about	an axis	so that	it
	       faces the eye as	much as	the axis constraint allows.

     GL_SPRITE_OBJECT_ALIGNED_SGIX    [Toc]    [Back]
	       The front of the	object is rotated about	a point	to face	the
	       eye. The	remaining rotational degree of freedom is specified by
	       aligning	the top	of the object with a specified axis in object
	       coordinates.

     GL_SPRITE_EYE_ALIGNED_SGIX    [Toc]    [Back]
	       The front of the	object is rotated about	a point	to face	the
	       eye. The	remaining rotational degree of freedom is specified by
	       aligning	the top	of the object with a specified axis in eye
	       coordinates.

     When pname	is either GL_SPRITE_AXIS_SGIX or GL_SPRITE_TRANSLATION_SGIX,
     params is a pointer to a four-element vector that specifies the sprite
     rotation axis or sprite translation, respectively.

     The rendering of sprite geometry is enabled with glEnable and disabled
     with glDisable using the constant GL_SPRITE_SGIX.

NOTES    [Toc]    [Back]

     When using	sprites, the current projection	matrix must not	include	a
     rotation.

     Be	aware that user-defined	clipping planes, texture coordinates produced
     by	certain	glTexGen modes,	and the	current	raster position	will be
     affected by the combined sprite and modelview transformation if they are
     specified while GL_SPRITE_SGIX is enabled.

     glSpriteParameterSGIX is part of the GL_SGIX_sprite extension, not	part
     of	the core GL command set.  See glIntro for information about using
     extensions.

ERRORS    [Toc]    [Back]

     GL_INVALID_ENUM is	generated if pname is not an accepted value.

     GL_INVALID_ENUM is	generated if glSpriteParameterfSGIX or
     glSpriteParameteriSGIX parameter pname is the GL_SPRITE_MODE_SGIX and
     parameter param is	not one	of the accepted	values.





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glSpriteParameterSGIX(3G)      OpenGL Reference	     glSpriteParameterSGIX(3G)



     GL_INVALID_OPERATION is generated if glSpriteParameterSGIX	is executed
     between the execution of glBegin and the corresponding execution of
     glEnd.

ASSOCIATED GETS    [Toc]    [Back]

     glIsEnabled with argument GL_SPRITE_SGIX
     glGet with	argument GL_SPRITE_MODE_SGIX
     glGet with	argument GL_SPRITE_AXIS_SGIX
     glGet with	argument GL_SPRITE_TRANSLATION_SGIX
     glGetString with argument GL_EXTENSIONS

SEE ALSO    [Toc]    [Back]

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