Re: [AD] correct behaviour for additive blending?

[Elias Pschernig <elias.pschernig@xxxxxxxxxx>]

On Sat, 2010-03-13 at 17:30 +1100, Peter Wang wrote:
> On 2010-03-13, Peter Wang <novalazy@xxxxxxxxxx> wrote:
> > 
> > I'll try it on a couple of other machines around here.
> 
> Ok, I couldn't reproduce the problem on a machine with the old open source
> ATI driver, nor on a machine with the proprietary Nvidia driver.  So it's
> probably specific to fglrx or maybe the configuration on that machine.
> 

Can you try this? It should also be wrong if the problem is in the
driver and not A5.

#include "allegro5/allegro5.h"
#include "allegro5/allegro_opengl.h"

struct V {
    float x, y;
    unsigned char r, g, b, a;
};

int main()
{
    ALLEGRO_DISPLAY *display;
    ALLEGRO_EVENT_QUEUE *queue;

    al_init();

    display = al_create_display(640, 480);
    
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);
    glEnable(GL_BLEND);
    
    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    
    struct V v[] = {
        {100, 150, 0, 50, 0, 255},
        {200, 150, 0, 50, 0, 255},
        {150, 100, 0, 50, 0, 255},
        {150, 200, 0, 50, 0, 255},
    };
    
    glBlendFuncSeparate(GL_ONE, GL_ONE, GL_ONE, GL_ONE);
    glBlendEquation(GL_FUNC_ADD);

    glVertexPointer(2, GL_FLOAT, sizeof(struct V), &v[0].x);
    glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(struct V), &v[0].r);
    
    glDrawArrays(GL_LINES, 0, 4);

    al_flip_display();

    queue = al_create_event_queue();
    al_register_event_source(queue, al_get_display_event_source(display));
    while (1) {
        ALLEGRO_EVENT event;
        al_wait_for_event(queue, &event);
        if (event.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
            break;
    }

    return 0;
}