using System;
using System.Text;

using sharpallegro;

namespace ex3buf
{
    class ex3buf : Allegro
    {
        const int NUM_SHAPES = 16;


        public class SHAPE
        {
            public int color;                        /* color of the shape */
            public int x, y;                         /* centre of the shape */
            public int dir1, dir2, dir3;             /* directions to the three corners */
            public int dist1, dist2, dist3;          /* distances to the three corners */
            public int xc, yc, ac;                   /* position and angle change values */
        }


        static SHAPE[] shapes = new SHAPE[NUM_SHAPES];
        static bool triplebuffer_not_available = false;



        /* randomly initialises a shape structure */
        static void init_shape(SHAPE shape)
        {
            shape.color = 1 + (AL_RAND() % 15);

            /* randomly position the corners */
            shape.dir1 = itofix(AL_RAND() % 256);
            shape.dir2 = itofix(AL_RAND() % 256);
            shape.dir3 = itofix(AL_RAND() % 256);

            shape.dist1 = itofix(AL_RAND() % 64);
            shape.dist2 = itofix(AL_RAND() % 64);
            shape.dist3 = itofix(AL_RAND() % 64);

            /* rand centre position and movement speed/direction */
            shape.x = itofix(AL_RAND() % SCREEN_W);
            shape.y = itofix(AL_RAND() % SCREEN_H);
            shape.ac = itofix((AL_RAND() % 9) - 4);
            shape.xc = itofix((AL_RAND() % 7) - 2);
            shape.yc = itofix((AL_RAND() % 7) - 2);
        }



        /* updates the position of a shape structure */
        static void move_shape(SHAPE shape)
        {
            shape.x += shape.xc;
            shape.y += shape.yc;

            shape.dir1 += shape.ac;
            shape.dir2 += shape.ac;
            shape.dir3 += shape.ac;

            if (((shape.x <= 0) && (shape.xc < 0)) ||
                ((shape.x >= itofix(SCREEN_W)) && (shape.xc > 0)))
            {
                shape.xc = -shape.xc;
                shape.ac = itofix((AL_RAND() % 9) - 4);
            }

            if (((shape.y <= 0) && (shape.yc < 0)) ||
                ((shape.y >= itofix(SCREEN_H)) && (shape.yc > 0)))
            {
                shape.yc = -shape.yc;
                shape.ac = itofix((AL_RAND() % 9) - 4);
            }
        }



        /* draws a frame of the animation */
        static void draw(BITMAP b)
        {
            int c;
            //char message[1024];
            string message;

            acquire_bitmap(b);

            clear_bitmap(b);

            for (c = 0; c < NUM_SHAPES; c++)
            {
                triangle(b,
                   fixtoi(shapes[c].x + fixmul(shapes[c].dist1,
                     fixcos(shapes[c].dir1))),
                   fixtoi(shapes[c].y + fixmul(shapes[c].dist1,
                     fixsin(shapes[c].dir1))),
                   fixtoi(shapes[c].x + fixmul(shapes[c].dist2,
                     fixcos(shapes[c].dir2))),
                   fixtoi(shapes[c].y + fixmul(shapes[c].dist2,
                     fixsin(shapes[c].dir2))),
                   fixtoi(shapes[c].x + fixmul(shapes[c].dist3,
                     fixcos(shapes[c].dir3))),
                   fixtoi(shapes[c].y + fixmul(shapes[c].dist3,
                     fixsin(shapes[c].dir3))),
                   shapes[c].color);

                move_shape(shapes[c]);
            }

            if (triplebuffer_not_available)
                //ustrzcpy(message, sizeof message, "Simulated triple buffering");
                message = "Simulated triple buffering";
            else
                //ustrzcpy(message, sizeof message, "Real triple buffering");
                message = "Real triple buffering";

            textout_ex(b, font, message, 0, 0, 255, -1);

            release_bitmap(b);
        }



        /* main animation control loop */
        static void triple_buffer(BITMAP page1, BITMAP page2, BITMAP page3)
        {
            BITMAP active_page = page1;
            int page = 0;

            do
            {
                /* draw a frame */
                draw(active_page);

                /* make sure the last flip request has actually happened */
                do
                {
                } while (poll_scroll());

                /* post a request to display the page we just drew */
                request_video_bitmap(active_page);

                /* update counters to point to the next page */
                switch (page)
                {
                    case 0: page = 1; active_page = page2; break;
                    case 1: page = 2; active_page = page3; break;
                    case 2: page = 0; active_page = page1; break;
                }

            } while (!keypressed());

            clear_keybuf();
        }



        static int Main()
        {
            BITMAP page1, page2, page3;
            int c;
            int w, h;

#if ALLEGRO_DOS
   w = 320;
   h = 240;
#else
            w = 640;
            h = 480;
#endif

            if (allegro_init() != 0)
                return 1;
            install_timer();
            install_keyboard();
            install_mouse();

            /* see comments in exflip.c */
#if ALLEGRO_VRAM_SINGLE_SURFACE
   if (set_gfx_mode(GFX_AUTODETECT, w, h, 0, h * 3) != 0) {
#else
            if (set_gfx_mode(GFX_AUTODETECT, w, h, 0, 0) != 0)
            {
#endif
                if (set_gfx_mode(GFX_SAFE, w, h, 0, 0) != 0)
                {
                    set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
                    allegro_message(string.Format("Unable to set any graphic mode\n{0}\n",
                        allegro_error));
                    return 1;
                }
            }

            set_palette(desktop_palette);

            /* if triple buffering isn't available, try to enable it */
            if ((gfx_capabilities & GFX_CAN_TRIPLE_BUFFER) == 0)
                enable_triple_buffer();

            /* if that didn't work, give up */
            if ((gfx_capabilities & GFX_CAN_TRIPLE_BUFFER) == 0)
            {
                triplebuffer_not_available = true;
            }

            /* allocate three sub bitmaps to access pages of the screen */
            page1 = create_video_bitmap(SCREEN_W, SCREEN_H);
            page2 = create_video_bitmap(SCREEN_W, SCREEN_H);
            page3 = create_video_bitmap(SCREEN_W, SCREEN_H);

            if ((!page1) || (!page2) || (!page3))
            {
                set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
                allegro_message("Unable to create three video memory pages\n");
                return 1;
            }

            /* initialise the shapes */
            for (c = 0; c < NUM_SHAPES; c++)
            {
                shapes[c] = new SHAPE();
                init_shape(shapes[c]);
            }

            triple_buffer(page1, page2, page3);

            destroy_bitmap(page1);
            destroy_bitmap(page2);
            destroy_bitmap(page3);

            return 0;
        }
    }
}