Tutorial 1: High Level Loading

This tutorial shows how to use the high level loading functions. Nearly all OpenGL and application code is stripped. Only some lines are left for orientation.

Data structure

First we need the header of course. To make it plain and simple we just use a global variable to hold the trimesh data:

#include "trimeshloader.h"

tlTrimesh *gTrimesh = NULL;

Load/Destroy

load the file provided by the user. if loading fails for some reason, NULL is returned:

int main()
{
    /* other code, setup opengl */

    gTrimesh = tlLoadTrimesh( argv[1] );
    if( gTrimesh == NULL )
        return 1;

    /* other code */

    while( running == 1 )
    {
        /* other code */
        draw();
        /* other code */
    }

    tlDeleteTrimesh( gTrimesh );

    /* other code */
}

Data access

Now we actually draw each object of the the trimesh. bind the vertex data with glVertexPointer, and provide indices to glDrawElements:

void draw()
{
    glPushMatrix();
    glRotatef( -90.0f, 1.0f, 0.0f, 0.0f );
    glColor3f( 0.0f, 0.0f, 1.0f );
    glEnableClientState( GL_VERTEX_ARRAY );
    glVertexPointer( 3, GL_FLOAT, gTrimesh->verticex_size, gTrimesh->vertices );
    for( i = 0; i < gTrimesh->object_count; i++)
    {
        glDrawElements( GL_TRIANGLES, gTrimesh->objects[i].face_count  * 3, GL_UNSIGNED_SHORT, gTrimesh->faces + gTrimesh->objects[i].face_index );
    }
    glDisableClientState( GL_VERTEX_ARRAY );
    glPopMatrix();
}