In es 1.0, I was able to use indexing into an existing vertex buffer in the glDrawElements method. This allowed me to specify only 4 points for drawing a square or rectangle. without the indexing I would have needed 6 points making up 2 triangles. How could I do this in ES 2.0?

satya - Fri Jul 27 2012 11:01:14 GMT-0400 (Eastern Daylight Time)

glVertexAttribPointer index

satya - Fri Jul 27 2012 11:01:42 GMT-0400 (Eastern Daylight Time)

a good attempt at stackoverflow

satya - Fri Jul 27 2012 11:15:32 GMT-0400 (Eastern Daylight Time)

Reusing vertices glVertexAttrib pointer

Search for: Reusing vertices glVertexAttrib pointer

satya - Fri Jul 27 2012 11:23:34 GMT-0400 (Eastern Daylight Time)

The index in glVertexAttribPointer referes to


#version 400
layout(location=0) in vec4 in_Position;
layout(location=1) in vec4 in_Color;
out vec4 ex_Color;
void main(void)
{
    gl_Position = in_Position;
    ex_Color = in_Color;
}

satya - Fri Jul 27 2012 11:24:33 GMT-0400 (Eastern Daylight Time)

refers to the location numbers indicating variable names

for instance the variable in_Position refers to the index of 0.

satya - Fri Jul 27 2012 12:29:18 GMT-0400 (Eastern Daylight Time)

Real nice. This may be the solution: IBO

satya - Fri Jul 27 2012 12:30:26 GMT-0400 (Eastern Daylight Time)

This is a superb effort:http://openglbook.com/

satya - Fri Jul 27 2012 12:34:24 GMT-0400 (Eastern Daylight Time)

GL_ELEMENT_ARRAY_BUFFER for indices?

Search for: GL_ELEMENT_ARRAY_BUFFER for indices?

satya - Fri Jul 27 2012 12:35:25 GMT-0400 (Eastern Daylight Time)

use glDrawElements and not glDrawArrays. There you go!

satya - Fri Jul 27 2012 12:35:44 GMT-0400 (Eastern Daylight Time)

glDrawElements

Search for: glDrawElements

satya - Fri Jul 27 2012 12:38:39 GMT-0400 (Eastern Daylight Time)

Signature of this function


void glDrawElements(   GLenum mode,
    GLsizei count,
    GLenum type,
    const GLvoid * indices);

Notice the indices argument.

satya - Fri Jul 27 2012 12:40:46 GMT-0400 (Eastern Daylight Time)

This function exists in the Android Binding as well