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/***************************************************************************

    Sega Hang On hardware

****************************************************************************

    Copyright Aaron Giles
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

        * Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.
        * Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in
          the documentation and/or other materials provided with the
          distribution.
        * Neither the name 'MAME' nor the names of its contributors may be
          used to endorse or promote products derived from this software
          without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY AARON GILES ''AS IS'' AND ANY EXPRESS OR
    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL AARON GILES BE LIABLE FOR ANY DIRECT,
    INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
    STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
    IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.

***************************************************************************/

#include "emu.h"
#include "includes/segahang.h"



//-------------------------------------------------
//  video_start - initialize the video system
//-------------------------------------------------

void segahang_state::video_start()
{
	// initialize the tile/text layers
	segaic16_tilemap_init(machine(), 0, SEGAIC16_TILEMAP_HANGON, 0x000, 0, 2);

	// initialize the road
	segaic16_road_init(machine(), 0, m_sharrier_video ? SEGAIC16_ROAD_SHARRIER : SEGAIC16_ROAD_HANGON, 0x038, 0x7c0, 0x7c0, 0);
}


//-------------------------------------------------
//  screen_update - render all graphics
//-------------------------------------------------

UINT32 segahang_state::screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
	// if no drawing is happening, fill with black and get out
	if (!segaic16_display_enable)
	{
		bitmap.fill(get_black_pen(machine()), cliprect);
		return 0;
	}

	// start the sprites drawing
	m_sprites->draw_async(cliprect);

	// reset priorities
	machine().priority_bitmap.fill(0, cliprect);

	// draw the low priority road layer
	segaic16_road_draw(0, bitmap, cliprect, SEGAIC16_ROAD_BACKGROUND);

	// draw background
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_BACKGROUND, 0, 0x01);
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_BACKGROUND, 1, 0x02);

	// draw foreground
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_FOREGROUND, 0, 0x02);
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_FOREGROUND, 1, 0x04);

	// draw the high priority road
	segaic16_road_draw(0, bitmap, cliprect, SEGAIC16_ROAD_FOREGROUND);

	// text layer
	// note that we inflate the priority of the text layer to prevent sprites
	// from drawing over the high scores
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_TEXT, 0, 0x08);
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_TEXT, 1, 0x08);

	// mix in sprites
	bitmap_ind16 &sprites = m_sprites->bitmap();
	for (const sparse_dirty_rect *rect = m_sprites->first_dirty_rect(cliprect); rect != NULL; rect = rect->next())
		for (int y = rect->min_y; y <= rect->max_y; y++)
		{
			UINT16 *dest = &bitmap.pix(y);
			UINT16 *src = &sprites.pix(y);
			UINT8 *pri = &machine().priority_bitmap.pix(y);
			
			// hangon mixing
			if (!m_sharrier_video)
			{
				for (int x = rect->min_x; x <= rect->max_x; x++)
				{
					// only process written pixels
					UINT16 pix = src[x];
					if (pix != 0xffff)
					{
						// compare sprite priority against tilemap priority
						int priority = pix >> 10;
						if ((1 << priority) > pri[x])
						{
							// if color bits are all 1, this triggers shadow/hilight
							if ((pix & 0x3f0) == 0x3f0)
								dest[x] += m_shadow ? m_palette_entries*2 : m_palette_entries;

							// otherwise, just add in sprite palette base
							else
								dest[x] = 1024 + (pix & 0x3ff);
						}
					}
				}
			}
			
			// sharrier mixing
			else
			{
				for (int x = rect->min_x; x <= rect->max_x; x++)
				{
					// only process written pixels
					UINT16 pix = src[x];
					if (pix != 0xffff)
					{
						// compare sprite priority against tilemap priority
						int priority = ((pix >> 9) & 2) | 1;
						if ((1 << priority) > pri[x])
						{
							// if shadow bit is 0 and pix data is 0xa, this triggers shadow/hilight
							if ((pix & 0x80f) == 0x00a)
								dest[x] += (m_paletteram[dest[x]] & 0x8000) ? m_palette_entries*2 : m_palette_entries;

							// otherwise, just add in sprite palette base
							else
								dest[x] = 1024 + (pix & 0x3ff);
						}
					}
				}
			}
		}

	return 0;
}