prog8/compiler/examples/mandelbrot.p8

%option enable_floats

~ main {

    sub start() -> ()   {

        const word width = 159
        const word height = 127
        word pixelx
        byte pixely
        float xx
        float yy
        float x
        float y
        float x2
        byte iter
        word plotx
        byte ploty

        _vm_gfx_clearscr(11)

        for pixely in 0 to height {         ; @todo 255 as upper limit doesn't work it overflows the loop
            for pixelx in 0 to width {
                xx=flt(pixelx)/width/3+0.2       ; @todo fix division to return float always, add // integer division
                yy=flt(pixely)/height/3.6+0.4

                x=0.0
                y=0.0

                for iter in 0 to 31 {
                    if(x*x + y*y > 4) break
                    x2 = x*x - y*y + xx
                    y=x*y*2 + yy
                    x=x2
                }

                plotx = pixelx*2
                ploty = pixely*2
                _vm_gfx_pixel(plotx, ploty, iter)
                _vm_gfx_pixel(plotx+1, ploty, iter)
                _vm_gfx_pixel(plotx, ploty+1, iter)
                _vm_gfx_pixel(plotx+1, ploty+1, iter)
            }
        }

        _vm_gfx_text(5, 5, 7, "Mandelbrot Fractal")
    }

}