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Color Array in VBO (Read 2553 times)
jeffg
Color Array in VBO
Feb 19th, 2010, 1:15pm  
Wondering if someone could point out my error here.  I'm testing out some VBO stuff and I can't quite get the color buffer matched up.  The vertex and element array seem to be working fine.  As a small example, I created three lines, which should (from left to right) be red, green, blue.  However, I get an mix of colors.  I'm also getting an error 1280 at top endDraw(): invalid enumerant if anyone knows what that is about.

Help get my color array working - Thanks!

Code:
import processing.opengl.*;
import javax.media.opengl.*;
import com.sun.opengl.util.*;
import java.nio.*;

PGraphicsOpenGL pgl;
GL gl;
int[] elements_vbo = new int[1];
int[] positions_vbo = new int[1];
int[] colors_vbo = new int[1];

void setup() {
  size( 400, 400, OPENGL );

  pgl = (PGraphicsOpenGL) g;
  gl = pgl.gl;

  //Vertexs - 6 vertexes, 3 floats xyz
  FloatBuffer pos  = BufferUtil.newFloatBuffer( 6 * 3 );
  pos.put( 100 );
  pos.put( 50 );
  pos.put( 0 );
  pos.put( 100 );
  pos.put( 300 );
  pos.put( 0 );
  pos.put( 200 );
  pos.put( 50 );
  pos.put( 0 );
  pos.put( 200 );
  pos.put( 300 );
  pos.put( 0 );
  pos.put( 300 );
  pos.put( 50 );
  pos.put( 0 );
  pos.put( 300 );
  pos.put( 300 );
  pos.put( 0 );
  pos.rewind();

  //Elements - 3 lines, 2 vertexs
  IntBuffer el  = BufferUtil.newIntBuffer( 3 * 2 );
  el.put( 0 );
  el.put( 1 );
  el.put( 2 );
  el.put( 3 );
  el.put( 4 );
  el.put( 5 );
  el.rewind();

  //Colors - 3 lines, 2 colors (one for each vertex - correct?), 4 floats rgba
  FloatBuffer col  = BufferUtil.newFloatBuffer( 3 * 2 * 4 );
  col.put( 1.0 );  //first line should be RED (1,0,0,1) * 2
  col.put( 0.0 );
  col.put( 0.0 );
  col.put( 1.0 );
  col.put( 1.0 );
  col.put( 0.0 );
  col.put( 0.0 );
  col.put( 1.0 );
  col.put( 0.0 );  //second line should be GREEN (0,1,0,1) * 2
  col.put( 1.0 );
  col.put( 0.0 );
  col.put( 1.0 );
  col.put( 0.0 );
  col.put( 1.0 );
  col.put( 0.0 );
  col.put( 1.0 );
  col.put( 0.0 );  //third line should be BLUE (0,0,1,1) * 2
  col.put( 0.0 );
  col.put( 1.0 );
  col.put( 1.0 );
  col.put( 0.0 );
  col.put( 0.0 );
  col.put( 1.0 );
  col.put( 1.0 );
  col.rewind();

  pgl.beginGL();

  gl.glGenBuffers( 1, positions_vbo, 0 );
  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, positions_vbo[0] );
  gl.glBufferData( GL.GL_ARRAY_BUFFER, 6 * 3 * BufferUtil.SIZEOF_FLOAT, pos, GL.GL_STATIC_DRAW );
  pos = null;
  
  gl.glGenBuffers( 1, elements_vbo, 0 );
  gl.glBindBuffer( GL.GL_ELEMENT_ARRAY_BUFFER, elements_vbo[0] );
  gl.glBufferData( GL.GL_ELEMENT_ARRAY_BUFFER, 3 * 2 * BufferUtil.SIZEOF_INT, el, GL.GL_STATIC_DRAW );   
  el = null;

  gl.glGenBuffers( 1, colors_vbo, 0 );
  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, colors_vbo[0] );
  gl.glBufferData( GL.GL_ARRAY_BUFFER, 3 * 2 * 4 * BufferUtil.SIZEOF_FLOAT, col, GL.GL_STATIC_DRAW );
  col = null;

  pgl.endGL();

}

void draw() {

  pgl.beginGL();
  gl.glLineWidth(10.0); 
  gl.glEnable (gl.GL_LINE_SMOOTH);
  gl.glEnableClientState(GL.GL_COLOR_ARRAY);
  gl.glEnableClientState(GL.GL_VERTEX_ARRAY);
  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, positions_vbo[0] );
  gl.glVertexPointer(3,GL.GL_FLOAT,0,0);
  gl.glBindBuffer( GL.GL_COLOR_ARRAY, colors_vbo[0] );
  gl.glColorPointer(4,GL.GL_FLOAT,0,0);
  gl.glBindBuffer( GL.GL_ELEMENT_ARRAY_BUFFER, elements_vbo[0] );
  gl.glDrawElements( GL.GL_LINES, 3 * 2, GL.GL_UNSIGNED_INT, 0 );  
  gl.glBindBuffer( gl.GL_ARRAY_BUFFER, 0);
  gl.glBindBuffer( gl.GL_ELEMENT_ARRAY_BUFFER, 0);
  gl.glDisableClientState(GL.GL_VERTEX_ARRAY);
  gl.glDisableClientState(GL.GL_COLOR_ARRAY);
  gl.glDisable (gl.GL_LINE_SMOOTH);
  pgl.endGL();
}

void stop()
{
  gl.glDeleteBuffers( 1, positions_vbo, 0 );
  gl.glDeleteBuffers( 1, colors_vbo, 0 );
  gl.glDeleteBuffers( 1, elements_vbo, 0 );
}
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« Last Edit: Mar 16th, 2010, 9:02am by jeffg »  
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jeffg
Re: Color Array in VBO
Reply #1 - Feb 19th, 2010, 2:13pm  
Figured it out... I had it out of order and I was calling a COLOR_ARRAY instead of an ARRAY_BUFFER.  I'm still not sure what the 1280 error was about but "hint(DISABLE_OPENGL_ERROR_REPORT);" removes it, though this may just be cutting the dashboard lights.

Code:
void draw() {
  pgl.beginGL();
  gl.glLineWidth(10.0); 
  gl.glEnable (gl.GL_LINE_SMOOTH);
  gl.glEnableClientState(GL.GL_COLOR_ARRAY);
  gl.glEnableClientState(GL.GL_VERTEX_ARRAY);
  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, colors_vbo[0] );
  gl.glColorPointer(4,GL.GL_FLOAT,0,0);
  gl.glBindBuffer( GL.GL_ARRAY_BUFFER, positions_vbo[0] );
  gl.glVertexPointer(3,GL.GL_FLOAT,0,0);
  gl.glBindBuffer( GL.GL_ELEMENT_ARRAY_BUFFER, elements_vbo[0] );
  gl.glDrawElements( GL.GL_LINES, 3 * 2, GL.GL_UNSIGNED_INT, 0 );  
  gl.glBindBuffer( gl.GL_ARRAY_BUFFER, 0);
  gl.glBindBuffer( gl.GL_ELEMENT_ARRAY_BUFFER, 0);
  gl.glDisableClientState(GL.GL_VERTEX_ARRAY);
  gl.glDisableClientState(GL.GL_COLOR_ARRAY);
  gl.glDisable (gl.GL_LINE_SMOOTH);
  pgl.endGL();
}
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« Last Edit: Mar 16th, 2010, 9:03am by jeffg »  
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jeffg
Re: Color Array in VBO
Reply #2 - Mar 16th, 2010, 7:41am  
Well, I thought I had figured it out.. but not quite.  The color array is somehow tied to the positions vertex array, and not the element array.  So, here is a new example, the bar that crosses should be orange, but instead it ties the color point to 0 and the color point to 5 making a gradient line.  Could someone straiten me out and get this forth line orange.

import processing.opengl.*;
import javax.media.opengl.*;
import com.sun.opengl.util.*;
import java.nio.*;

PGraphicsOpenGL pgl;
GL gl;
int[] elements_vbo = new int[1];
int[] positions_vbo = new int[1];
int[] colors_vbo = new int[1];

void setup() {
 size( 400, 400, OPENGL );

 pgl = (PGraphicsOpenGL) g;
 gl = pgl.gl;

 //Vertexs - 6 vertexes, 3 floats xyz
 FloatBuffer pos  = BufferUtil.newFloatBuffer( 6 * 3 );
 pos.put( 100 );
 pos.put( 50 );
 pos.put( 0 );
 pos.put( 100 );
 pos.put( 300 );
 pos.put( 0 );
 pos.put( 200 );
 pos.put( 50 );
 pos.put( 0 );
 pos.put( 200 );
 pos.put( 300 );
 pos.put( 0 );
 pos.put( 300 );
 pos.put( 50 );
 pos.put( 0 );
 pos.put( 300 );
 pos.put( 300 );
 pos.put( 0 );
 pos.rewind();

 //Elements - 4 lines, 2 vertexs
 IntBuffer el  = BufferUtil.newIntBuffer( 4 * 2 );
 el.put( 0 );
 el.put( 1 );
 el.put( 2 );
 el.put( 3 );
 el.put( 4 );
 el.put( 5 );
 el.put( 0 );
 el.put( 5 );
 el.rewind();

 //Colors - 4 lines, 2 colors (one for each vertex - correct?), 4 floats rgba
 FloatBuffer col  = BufferUtil.newFloatBuffer( 4 * 2 * 4 );
 col.put( 1.0 );  //first line should be RED (1,0,0,1) * 2
 col.put( 0.0 );
 col.put( 0.0 );
 col.put( 1.0 );
 col.put( 1.0 );
 col.put( 0.0 );
 col.put( 0.0 );
 col.put( 1.0 );
 col.put( 0.0 );  //second line should be GREEN (0,1,0,1) * 2
 col.put( 1.0 );
 col.put( 0.0 );
 col.put( 1.0 );
 col.put( 0.0 );
 col.put( 1.0 );
 col.put( 0.0 );
 col.put( 1.0 );
 col.put( 0.0 );  //third line should be BLUE (0,0,1,1) * 2
 col.put( 0.0 );
 col.put( 1.0 );
 col.put( 1.0 );
 col.put( 0.0 );
 col.put( 0.0 );
 col.put( 1.0 );
 col.put( 1.0 );
 col.put( 1.0 );  //forth line should be ORANGE (1,.5,0,1) * 2
 col.put( 0.5 );
 col.put( 0.0 );
 col.put( 1.0 );
 col.put( 1.0 );
 col.put( 0.5 );
 col.put( 0.0 );
 col.put( 1.0 );
 col.rewind();

 pgl.beginGL();

 gl.glGenBuffers( 1, positions_vbo, 0 );
 gl.glBindBuffer( GL.GL_ARRAY_BUFFER, positions_vbo[0] );
 gl.glBufferData( GL.GL_ARRAY_BUFFER, 6 * 3 * BufferUtil.SIZEOF_FLOAT, pos, GL.GL_STATIC_DRAW );
 pos = null;
 
 gl.glGenBuffers( 1, elements_vbo, 0 );
 gl.glBindBuffer( GL.GL_ELEMENT_ARRAY_BUFFER, elements_vbo[0] );
 gl.glBufferData( GL.GL_ELEMENT_ARRAY_BUFFER, 4 * 2 * BufferUtil.SIZEOF_INT, el, GL.GL_STATIC_DRAW );  
 el = null;

 gl.glGenBuffers( 1, colors_vbo, 0 );
 gl.glBindBuffer( GL.GL_ARRAY_BUFFER, colors_vbo[0] );
 gl.glBufferData( GL.GL_ARRAY_BUFFER, 4 * 2 * 4 * BufferUtil.SIZEOF_FLOAT, col, GL.GL_STATIC_DRAW );
 col = null;

 pgl.endGL();

}

void draw() {
 pgl.beginGL();
 gl.glLineWidth(10.0);
 gl.glEnable (gl.GL_LINE_SMOOTH);
 gl.glEnableClientState(GL.GL_COLOR_ARRAY);
 gl.glEnableClientState(GL.GL_VERTEX_ARRAY);
 gl.glBindBuffer( GL.GL_ARRAY_BUFFER, colors_vbo[0] );
 gl.glColorPointer(4,GL.GL_FLOAT,0,0);
 gl.glBindBuffer( GL.GL_ARRAY_BUFFER, positions_vbo[0] );
 gl.glVertexPointer(3,GL.GL_FLOAT,0,0);
 gl.glBindBuffer( GL.GL_ELEMENT_ARRAY_BUFFER, elements_vbo[0] );
 gl.glDrawElements( GL.GL_LINES, 4 * 2, GL.GL_UNSIGNED_INT, 0 );  
 gl.glBindBuffer( gl.GL_ARRAY_BUFFER, 0);
 gl.glBindBuffer( gl.GL_ELEMENT_ARRAY_BUFFER, 0);
 gl.glDisableClientState(GL.GL_VERTEX_ARRAY);
 gl.glDisableClientState(GL.GL_COLOR_ARRAY);
 gl.glDisable (gl.GL_LINE_SMOOTH);
 pgl.endGL();
}

void stop()
{
 gl.glDeleteBuffers( 1, positions_vbo, 0 );
 gl.glDeleteBuffers( 1, colors_vbo, 0 );
 gl.glDeleteBuffers( 1, elements_vbo, 0 );
}
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« Last Edit: Mar 16th, 2010, 11:27am by jeffg »  
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V
Re: Color Array in VBO
Reply #3 - Mar 16th, 2010, 3:34pm  
your element index list will index into the vertex and color array
for example the first line picks vertex 0 and vertex 1 from the vertexlist.
it will also pick the color0 and color 1 from the color list..

what you need is duplicate vertex position and different colors.

hope that helps,

have fun.
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Victor Martins | www.pixelnerve.com/v
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jeffg
Re: Color Array in VBO
Reply #4 - Mar 16th, 2010, 3:51pm  
This does clarify things... and gives me some other ways I might try to implement it.  It looks like, at least for the lines, this would be better implemented as a glDrawArray.  I can then create a index on the unique vertexes.
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V
Re: Color Array in VBO
Reply #5 - Mar 16th, 2010, 4:14pm  
just think of it this way:
if your have a vertex that for some reason has different component values, color, texcoord, tangent, whatever.. in practice it is a different vertex.
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Victor Martins | www.pixelnerve.com/v
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