Hi folks,

based on Eric Wing's patch, I created the attached patch which fixes
the OpenGL coordinate inversion bug in SDL. It works fine over here on
10.3 with Ryan's test program (which I also attached).

There is another change in it: I removed the "- 1" in the two lines
using CGDisplayPixelsHigh()... while I understand from a logical point
of view why they *should* be correct, I checked the actual values
computed that way, and they were off-by-one. After removing the " - 1",
the returned mouse coordinates are correct. I checked this by moving
the mouse to the screen top/bottom in fullscreen mode, BTW. With the
change, the proper values 0 and 479 are returned (in 640x480 mode).

Sam, you may still want to test on 10.1, it's very simple using Ryan's
minimal test code :-)

Cheers,

Max




(Here is the reproduction case for revision history's sake...)


/*
 * To compile:
 *   gcc -o test test.c `sdl-config --cflags` `sdl-config --libs` -framework OpenGL
 *
 *  --ryan.
 */

#include <stdio.h>
#include "SDL.h"
#include "SDL_opengl.h"

int main(int argc, char **argv)
{
    Uint32 flags = SDL_OPENGL /* | SDL_FULLSCREEN */;
    SDL_Surface *screen;
    SDL_Event event;
    int done = 0;
    GLfloat ratio;

    SDL_Init(SDL_INIT_VIDEO);
    SDL_ShowCursor(0);
    if ((argv[1]) && (strcmp(argv[1], "--grab") == 0))
        SDL_WM_GrabInput(SDL_GRAB_ON);
    screen = SDL_SetVideoMode(640, 480, 0, flags);
    if (!screen)
        return(42);

    ratio = ((GLfloat) screen->w) / ((GLfloat) screen->h);
    glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
    glClearDepth( 1.0f );
    glEnable( GL_DEPTH_TEST );
    glDepthFunc( GL_LEQUAL );
    glViewport( 0, 0, screen->w, screen->h);
    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    gluPerspective( 45.0f, ratio, 0.1f, 100.0f );
    glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    SDL_GL_SwapBuffers();


    // eh, close enough.
    #define MAX_X 6.12
    #define MAX_Y 4.50

    while (!done)
    {
        int x, y;
        GLfloat glx, gly;

        if (!SDL_WaitEvent(&event))
            break;

        switch (event.type)
        {
            case SDL_KEYUP:
                if (event.key.keysym.sym == SDLK_ESCAPE)
                    done = 1;
                break;
        }

        SDL_GetMouseState(&x, &y);
        glx = ((((GLfloat) x) / ((GLfloat) screen->w)) - 0.5f) * MAX_X;
        gly = ((((GLfloat) y) / ((GLfloat) screen->h)) - 0.5f) * MAX_Y;

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    	glLoadIdentity();
        glTranslatef(glx,-gly,-6.0f);

        glBegin(GL_TRIANGLES);
            glColor3f(1,0,0); glVertex3f( 0.00f,  0.25f, 0.00f);
            glColor3f(0,1,0); glVertex3f(-0.25f, -0.25f, 0.00f);
            glColor3f(0,0,1); glVertex3f( 0.25f, -0.25f, 0.00f);
	    glEnd();

        SDL_GL_SwapBuffers();
    }

    SDL_Quit();
    return(0);
}

/* end of test.c ... */