hi i have same problem with custom atributes HELP

This topic contains 2 replies, has 2 voices, and was last updated by  malkia 8 years, 3 months ago.

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  • #29846

    hello all !

    i try set atributes on vertex

    shader:

    Code:
    uniform mat4 u_mvpMatrix;

    attribute vec4 a_position;       

           

          void main()                                 

          {       

            gl_Position = u_mvpMatrix* a_position;

          }

    and code init

    Code:
    loading init shader ….

    and

    mvpLoc = glGetUniformLocation( prog, “u_mvpMatrix” );

    a_position = glGetAttribLocation(prog, “a_position”);

    glEnableVertexAttribArray(a_position);

    draw code

    Code:
         glUniformMatrix4fv( mvpLoc, 1, GL_FALSE, (GLfloat*) &mvpMatrix.m[0][0] );

         glVertexAttribPointer(a_position,4,GL_FLOAT,0,0,position);

         glDrawElements(GL_TRIANGLES, 3*numIndicles, GL_UNSIGNED_SHORT, &Indicles);

    struct position

    Code:
    typedef struct

    {

       float x,y,z,w;

    }positionStruct;

    positionStruct*position;

    position[0].x = 0;

    position[0].y = 0;

    position[0].z = 0;

    position[0].w = 0;

    position[1].x = 1;

    position[1].y = 0;

    position[1].z = 0;

    position[1].w = 0;

    position[2].x = 2;

    position[2].y = 0;

    position[2].z = 0;

    position[2].w = 0;

    ets ….

    The primitive thing not to be displayed

    but if i del

    Code:
    glVertexAttribPointer(a_position,4,GL_FLOAT,0,0,position);

    primitive to be displayed normally

    how correct set attributes array on vertex ? idarkstranger2009-07-02 19:47:17

    #33198

    aaaaaa GURU help me !!!! i try correct my problem Some days ((((((( plz help !

    #33199

    malkia
    Member

    Well there could be different things going on here. Only part of the source code is posted.

    In anycase:
       – Do you have proper texture shader?
       – Are your vertices fine? (Looking at them it looks like degenerate triangle)
       – You are talking about triangle, yet you are passing 4 vertices (but only 3 are initialized)
       – Check your CCW/CW culling – or better turn it off for now.

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