prog8/compiler/examples/cube3d.p8

%option enable_floats

~ irq {
    word global_time
    byte time_changed

    sub irq() {
        global_time++
        time_changed = 1
    }
}


~ main {

    const word width = 320
    const word height = 200

    ; vertices
    float[8] xcoor = [ -1.0, -1.0, -1.0, -1.0,  1.0,  1.0,  1.0, 1.0 ]
    float[8] ycoor = [ -1.0, -1.0,  1.0,  1.0, -1.0, -1.0,  1.0, 1.0 ]
    float[8] zcoor = [ -1.0,  1.0, -1.0,  1.0, -1.0,  1.0, -1.0, 1.0 ]

    ; edges (msb=from vertex, lsb=to vertex)
    word[12] edges = [$0001, $0103, $0302, $0200, $0405, $0507, $0706, $0604, $0004, $0105, $0206, $0307]

    ; storage for rotated coordinates
    float[len(xcoor)] rotatedx
    float[len(ycoor)] rotatedy
    float[len(zcoor)] rotatedz

    ; general index var
    byte i

    sub start()  {
        if irq.time_changed {
            irq.time_changed = 0
            _vm_gfx_clearscr(0)
            _vm_gfx_text(14, 5, 5, "Spin to Win !!!")

            for i in 0 to width//10 {
                _vm_gfx_line(i*2+width//2-width//10, 130, i*10, 199, 6)
            }

            rotate_vertices(flt(irq.global_time) / 30.0)
            draw_edges()

        }
        goto start
    }

    sub rotate_vertices(t: float) {
        ; rotate around origin (0,0,0)

        ; set up the 3d rotation matrix values
        float cosa = cos(t)
        float sina = sin(t)
        float cosb = cos(t*0.33)
        float sinb = sin(t*0.33)
        float cosc = cos(t*0.78)
        float sinc = sin(t*0.78)

        float Axx = cosa*cosb
        float Axy = cosa*sinb*sinc - sina*cosc
        float Axz = cosa*sinb*cosc + sina*sinc
        float Ayx = sina*cosb
        float Ayy = sina*sinb*sinc + cosa*cosc
        float Ayz = sina*sinb*cosc - cosa*sinc
        float Azx = -sinb
        float Azy = cosb*sinc
        float Azz = cosb*cosc

        for i in 0 to len(xcoor)-1 {
            rotatedx[i] = Axx*xcoor[i] + Axy*ycoor[i] + Axz*zcoor[i]
            rotatedy[i] = Ayx*xcoor[i] + Ayy*ycoor[i] + Ayz*zcoor[i]
            rotatedz[i] = Azx*xcoor[i] + Azy*ycoor[i] + Azz*zcoor[i]
        }
    }


    sub draw_edges() {
        word edge
        byte e_from
        byte e_to

        sub toscreenx(x: float, z: float) -> word {
            return floor(x/(4.2+z) * flt(height)) + width // 2
        }

        sub toscreeny(y: float, z: float) -> word {
            return floor(y/(4.2+z) * flt(height)) + height // 2
        }

        ; draw all edges of the object
        for edge in edges {
            e_from = msb(edge)
            e_to = lsb(edge)
            _vm_gfx_line(toscreenx(rotatedx[e_from], rotatedz[e_from]), toscreeny(rotatedy[e_from], rotatedz[e_from]),
                         toscreenx(rotatedx[e_to], rotatedz[e_to]), toscreeny(rotatedy[e_to], rotatedz[e_to]), e_from+e_to)
        }

        ; accentuate the vertices a bit with small boxes
        word sx
        word sy
        byte col
        for i in 0 to len(xcoor)-1 {
            sx = toscreenx(rotatedx[i], rotatedz[i])
            sy = toscreeny(rotatedy[i], rotatedz[i])
            col=i+2
            _vm_gfx_pixel(sx-1, sy-1, col)
            _vm_gfx_pixel(sx, sy-1, col)
            _vm_gfx_pixel(sx+1, sy-1, col)
            _vm_gfx_pixel(sx-1, sy, col)
            _vm_gfx_pixel(sx, sy, col)
            _vm_gfx_pixel(sx+1, sy, col)
            _vm_gfx_pixel(sx-1, sy+1, col)
            _vm_gfx_pixel(sx, sy+1, col)
            _vm_gfx_pixel(sx+1, sy+1, col)

            _vm_gfx_pixel(sx, sy-2, col)
            _vm_gfx_pixel(sx+2, sy, col)
            _vm_gfx_pixel(sx, sy+2, col)
            _vm_gfx_pixel(sx-2, sy, col)
        }
    }
}