Points and GLSL

• Subject: Points and GLSL
• From: "Wesley Smith" <email@hidden>
• Date: Thu, 17 May 2007 12:27:42 -0700
• Delivered-to: email@hidden
• Delivered-to: email@hidden
• Dkim-signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=IMWD5/fCNwGDy6ZHN/iXDZ3yu9RfTAT5nLbDWZyOQ7Znpa8CFVQep94GTJ1SrK6syVrUoQuvKbUkomSnVl91fwDUp+93CR/Qrw9auDIJKLJXaSlGGQmx6sJRz7duvVHRX360MyRKKZBrmWVla8Mepp6XWsOvQKpDVNHTeMOYVQk=
• Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=rR9T273SoATzhf1xmVHmjF/9KmmlhP3kNy3l/eXLBcMQqiFEJn8ELDlOm9MFqDDCSpm7Odd8GPvdOCTPFoWdJV24RQ+ce8O+BHhK7N1FwzNnuL5dg71IUf07gx1mbuyp0PtmWhXnHaGtFHwH8KECTpNitoizgrmX4SrEo+BzyEU=

I'm getting some very bizarre behavior with glTexenvi(GL_POINT_SPRITE,
GL_COORD_REPLACE, GL_TRUE).  I've found nothing in the shader specs of
the point parameter specs that would indicate a lack of support for
varying parameters passed from vertex to fragment program with the
above call.  My goal is to get access to the point sprite texture
coordinates and the point's actual position in world space into a
fragment shader for rendering pseudo 3D forms procedurally.

The issue I'm coming across is that if I pass say:

varying vec3 P; //world space position

to my fragment shader and try to use it in the fragment program, I
lose the texture coordinate variation across the point sprite.  Say
it's something like:

varying vec2 texcoord0;
varying vec3 P;
uniform vec3 eyePos;

void main(void)
{
   vec3 V = P-eyePos;
 gl_FragColor = vec4(texcoord0.xy, 0., 1.);
}

This will give me a green sprite.

varying vec2 texcoord0;
varying vec3 P;
uniform vec3 eyePos;

void main(void)
{
 //  vec3 V = P-eyePos;
 gl_FragColor = vec4(texcoord0.xy, 0., 1.);
}

this will give me a sprite that varies from black to yellow as
expected.  Any ideas or pointers to parts of the spec that I'm
overlooking?

thanks,
wes
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Mac-opengl mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/mac-opengl/email@hidden

• Follow-Ups:
  • Re: Points and GLSL
    • From: "Wesley Smith" <email@hidden>

• Prev by Date: Re: shaders and projected depth maps
• Next by Date: Re: shaders and projected depth maps
• Previous by thread: Re: shaders and projected depth maps
• Next by thread: Re: Points and GLSL
• Index(es):
  • Date
  • Thread