// license:BSD-3-Clause // copyright-holders:Aaron Giles /*************************************************************************** Sega Y-board hardware ***************************************************************************/ #include "emu.h" #include "includes/segaybd.h" //************************************************************************** // VIDEO STARTUP //************************************************************************** void segaybd_state::video_start() { // initialize the rotation layer m_segaic16vid->rotate_init(0, segaic16_video_device::ROTATE_YBOARD, 0x000); m_ysprites->set_rotate_ptr(m_segaic16vid->m_rotate); } //************************************************************************** // VIDEO UPDATE //************************************************************************** uint32_t segaybd_state::screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect) { // if no drawing is happening, fill with black and get out if (!m_segaic16vid->m_display_enable) { bitmap.fill(m_palette->black_pen(), cliprect); return 0; } // start the sprites drawing rectangle yboard_clip(0, 511, 0, 511); m_ysprites->bitmap().fill(0xffff); m_ysprites->draw_async(yboard_clip); m_bsprites->draw_async(cliprect); // apply rotation m_segaic16vid->rotate_draw(0, bitmap, cliprect, screen.priority(), m_ysprites->bitmap()); // mix in 16B sprites bitmap_ind16 &sprites = m_bsprites->bitmap(); for (const sparse_dirty_rect *rect = m_bsprites->first_dirty_rect(cliprect); rect != nullptr; rect = rect->next()) for (int y = rect->min_y; y <= rect->max_y; y++) { uint16_t *dest = &bitmap.pix(y); uint16_t *src = &sprites.pix(y); uint8_t *pri = &screen.priority().pix(y); for (int x = rect->min_x; x <= rect->max_x; x++) { // only process written pixels uint16_t pix = src[x]; if (pix != 0xffff) { // the 16b priority bits are stored like this // int colpri = ((data[4] & 0xff) << 4) | (((data[1] >> 9) & 0xf) << 12); // so PPPPppppppppcccc (P = priority p = palette c = colour data) // for Y board the (((data[1] >> 9) & 0xf) << 12) bit is the part we care about // the format of the screen.priority() buffer (populated in rotate_draw) is // ccc----- Sprite color // ---rrrr- Sprite priority // -------1 'was Indirected color data' before rotate_draw, forced to 1 when filling pri buffer // compare sprite priority against tilemap priority int priority = (pix >> 11) & 0x1e; if (priority < (pri[x] & 0x1f)) { // if the color is set to maximum, shadow pixels underneath us if ((pix & 0xf) == 0xe) dest[x] += m_palette_entries; // otherwise, just add in sprite palette base else dest[x] = 0x800 | (pix & 0x7ff); } } } } return 0; }