glBegin/glEnd to glDrawArrays
Author
I have some code that looks like this
glBegin(GL_TRIANGLES);
for (x=0 ...) {
glVertex3f(vertex[polygon[x].a].x,
vertex[polygon[x].a].y,
vertex[polygon[x].a].z);
glVertex3f(vertex[polygon[x].b].x,
vertex[polygon[x].b].y,
vertex[polygon[x].b].z);
glVertex3f(vertex[polygon[x].c].x,
vertex[polygon[x].c].y,
vertex[polygon[x].c].z);
}
glEnd();
but I can't use anymore glBegin/glEnd. The code must be rewrite using glDrawArrays or smth else... Any idea how to make this ?
You already have collected your vertexes and polygon indexes into 2 arrays. What you have to do now is:
INT iNumIndices = 3 * NumPolygons;
glEnableClientState( GL_VERTEX_ARRAY );
glVertexPointer( 3, GL_FLOAT, 0, (GLvoid *)vertex );
glDrawElements( GL_TRIANGLES, iNumIndices, GL_UNSIGNED_SHORT, (GLvoid *)polygon );
glDisableClientState( GL_VERTEX_ARRAY );
change GL_UNSIGNED_SHORT and GL_FLOAT with the proper enum ID for vertex and indexes components data type and change the magic number "3" into 4 if you are using 4 components for vertexes coordinates (X,Y,Z and W).
Notice that you can avoid call any time glEnableClientState() / glDisableClientState() if you are using this system to draw all your objects. In such case it is enough to you to call glEnableClientState() once during the application setup and call glDisableClientState() during the cleanup.
I hope this can help.
INT iNumIndices = 3 * NumPolygons;
glEnableClientState( GL_VERTEX_ARRAY );
glVertexPointer( 3, GL_FLOAT, 0, (GLvoid *)vertex );
glDrawElements( GL_TRIANGLES, iNumIndices, GL_UNSIGNED_SHORT, (GLvoid *)polygon );
glDisableClientState( GL_VERTEX_ARRAY );
change GL_UNSIGNED_SHORT and GL_FLOAT with the proper enum ID for vertex and indexes components data type and change the magic number "3" into 4 if you are using 4 components for vertexes coordinates (X,Y,Z and W).
Notice that you can avoid call any time glEnableClientState() / glDisableClientState() if you are using this system to draw all your objects. In such case it is enough to you to call glEnableClientState() once during the application setup and call glDisableClientState() during the cleanup.
I hope this can help.
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