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Index › Programming Questions & Help › OpenGL and 3D Libraries › glsl gl_PointSize not working (Solved)
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glsl gl_PointSize not working? (Solved) (Read 2074 times)
jeffg
glsl gl_PointSize not working? (Solved)
Mar 18th, 2010, 7:01pm  
I've been trying all night to get gl_PointSize to work with no luck.  The point size only seems to respond to gl.glPointSize(10);
Using  gl.glEnable(gl.GL_VERTEX_PROGRAM_POINT_SIZE);

Here is my vertex shader
void main() {
   //gl_Position = ftransform();
   gl_PointSize = 20.0;
}
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« Last Edit: Mar 19th, 2010, 1:33pm by jeffg »  
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JohnG
Re: glsl gl_PointSize not working?
Reply #1 - Mar 19th, 2010, 7:35am  
In experiments I did a while ago, different video cards have different limits to the point size. You can make them appear bigger on screen by playing with gl.glPointParameterfv(GL.GL_POINT_DISTANCE_ATTENUATION..... ) things, but that's some dark voodoo that I never got working properly.
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jeffg
Re: glsl gl_PointSize not working?
Reply #2 - Mar 19th, 2010, 9:15am  
Ya, I tried GL.GL_POINT_DISTANCE_ATTENUATION, but kept getting a weird flickering.  I also couldn't quite figure out the quadratic, no one bothers to explain what's happening.
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jeffg
Re: glsl gl_PointSize not working?
Reply #3 - Mar 19th, 2010, 12:37pm  
I think I've got it...  Grin
PDE
Code:

gl.glEnable(GL.GL_POINT_SPRITE);
gl.glEnable(gl.GL_VERTEX_PROGRAM_POINT_SIZE);
shader.startShader();
gl.glUniform1f(shader.getUniformLocation("pointSize"), 100.0);
gl.glTexEnvi(GL.GL_POINT_SPRITE, GL.GL_COORD_REPLACE, GL.GL_TRUE);
gl.glColor3f(1, 1, 1);
ringImg.enable();
ringImg.bind();
gl.glBindBuffer( GL.GL_ARRAY_BUFFER,  nodes_vbo[0]);
gl.glVertexPointer(3,GL.GL_FLOAT,0,0);
gl.glBindBuffer( GL.GL_ELEMENT_ARRAY_BUFFER, nelements_vbo[0] );
gl.glEnableClientState(GL.GL_VERTEX_ARRAY);
gl.glDrawElements( GL.GL_POINTS, vnodelength, GL.GL_UNSIGNED_INT, 0 );
...

Vertex Shader
Code:
uniform float pointSize;
void main() {
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
    vec4 mod = vec4( gl_ModelViewMatrix * gl_Vertex );
    gl_PointSize = 200.0 * pointSize/ -mod.z ;
    gl_FrontColor = gl_Color;
}
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« Last Edit: Mar 20th, 2010, 5:47am by jeffg »  
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