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added proper x-scroll handling for the decocass background, and some notes for further cleanup work regarding the background 'tilemap' - this improves Manhattan and several others.

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This commit is contained in:
David Haywood 2012-12-25 13:19:40 +00:00
parent b4da179247
commit 3ff105509c
3 changed files with 100 additions and 48 deletions
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12
src/mame/drivers/decocass.c
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@ -110,12 +110,12 @@ static ADDRESS_MAP_START( decocass_map, AS_PROGRAM, 8, decocass_state )
AM_RANGE(0xe400, 0xe400) AM_WRITE(decocass_reset_w)
/* BIO-3 board */
AM_RANGE(0xe402, 0xe402) AM_WRITE(decocass_mode_set_w)
AM_RANGE(0xe403, 0xe403) AM_WRITE(decocass_back_h_shift_w)
AM_RANGE(0xe404, 0xe404) AM_WRITE(decocass_back_vl_shift_w)
AM_RANGE(0xe405, 0xe405) AM_WRITE(decocass_back_vr_shift_w)
AM_RANGE(0xe406, 0xe406) AM_WRITE(decocass_part_h_shift_w)
AM_RANGE(0xe407, 0xe407) AM_WRITE(decocass_part_v_shift_w)
AM_RANGE(0xe402, 0xe402) AM_WRITE(decocass_mode_set_w) /* scroll mode regs + various enable regs */
AM_RANGE(0xe403, 0xe403) AM_WRITE(decocass_back_h_shift_w) /* back (both) tilemap x scroll */
AM_RANGE(0xe404, 0xe404) AM_WRITE(decocass_back_vl_shift_w) /* back (left) (top@rot0) tilemap y scroll */
AM_RANGE(0xe405, 0xe405) AM_WRITE(decocass_back_vr_shift_w) /* back (right) (bot@rot0) tilemap y scroll */
AM_RANGE(0xe406, 0xe406) AM_WRITE(decocass_part_h_shift_w) /* headlight */
AM_RANGE(0xe407, 0xe407) AM_WRITE(decocass_part_v_shift_w) /* headlight */
AM_RANGE(0xe410, 0xe410) AM_WRITE(decocass_color_center_bot_w)
AM_RANGE(0xe411, 0xe411) AM_WRITE(decocass_center_h_shift_space_w)

2
src/mame/includes/decocass.h
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@ -244,7 +244,7 @@ private:
DECLARE_READ8_MEMBER(decocass_nodong_r);
UINT8* m_type1_map;
void draw_edge(bitmap_ind16 &bitmap, const rectangle &cliprect, int which, bool opaque);
void draw_object(bitmap_ind16 &bitmap, const rectangle &cliprect);
void draw_center(bitmap_ind16 &bitmap, const rectangle &cliprect);
void mark_bg_tile_dirty(offs_t offset);

134
src/mame/video/decocass.c
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@ -2,6 +2,16 @@
DECO Cassette System video
The video system has clearly been designed for Highway Chase,
which unsurprisingly is the first game on the system. The
background 'tilemap' is very much like the road layer on the
standalone Highway Chase with a concept of left/right edges
with semi-independent scrolling, and the ability to transition
between scrolling different sections.
Additionally it supports the headlight effect also needed for
a Highway Chase style game.
***********************************************************************/
#include "emu.h"
@ -460,6 +470,80 @@ void decocass_state::draw_missiles(bitmap_ind16 &bitmap, const rectangle &clipre
}
}
// we could still massively clean up the background tilemap handling, I have a feeling the
// code to ignore tiles with 0x80 set on the left tilemap etc. is just a convenient hack
// to stop garbage tiles appearing when scrolling due to the weird ram layout and clipping rules
// 0 is left edge, 1 is right edge
void decocass_state::draw_edge(bitmap_ind16 &bitmap, const rectangle &cliprect, int which, bool opaque)
{
rectangle clip;
bitmap_ind16* srcbitmap;
int scrolly_l = m_back_vl_shift;
int scrolly_r = 256 - m_back_vr_shift;
// bit 0x04 of the mode select effectively selects between two banks of data
if (0 == (m_mode_set & 0x04))
scrolly_r += 256;
else
scrolly_l += 256;
int scrollx = 256 - m_back_h_shift;
int scrolly;
if (which==0)
{
clip = m_bg_tilemap_l_clip;
clip &= cliprect;
scrolly = scrolly_l;
srcbitmap = &m_bg_tilemap_l->pixmap();
}
else
{
clip = m_bg_tilemap_r_clip;
clip &= cliprect;
scrolly = scrolly_r;
srcbitmap = &m_bg_tilemap_r->pixmap();
}
int y,x;
// printf("m_mode_set %d\n", m_mode_set & 0x3);
// technically our y drawing probably shouldn't wrap / mask, but simply draw the 128pixel high 'edge' at the requested position
// see note above this funciton
for (y=clip.min_y; y<=clip.max_y;y++)
{
int srcline = (y + scrolly) & 0x1ff;
UINT16* src = &srcbitmap->pix16(srcline);
UINT16* dst = &bitmap.pix16(y);
for (x=clip.min_x; x<=clip.max_x;x++)
{
int srccol;
// 2 bits control the x scroll mode, allowing it to wrap either half of the tilemap, or transition one way or the other between the two halves
switch (m_mode_set & 3)
{
case 0x00: srccol = ((x + scrollx) & 0xff); break; // hwy normal case
case 0x01: srccol = (x + scrollx + 0x100) & 0x1ff; break; // manhattan building top
case 0x02: srccol = ((x + scrollx) & 0xff) + 0x100; break; // manhattan normal case
case 0x03: srccol = (x + scrollx) & 0x1ff; break; // hwy, burnrub etc.
}
UINT16 pix = src[srccol];
if ((pix & 0x3) || opaque)
{
dst[x] = pix;
}
}
}
}
void decocass_state::video_start()
{
@ -477,7 +561,7 @@ void decocass_state::video_start()
m_bg_tilemap_r_clip = machine().primary_screen->visible_area();
m_bg_tilemap_r_clip.min_y = 256 / 2;
/* background videroam bits D0-D3 are shared with the tileram */
/* background videoram bits D0-D3 are shared with the tileram */
m_bgvideoram = m_tileram;
m_bgvideoram_size = 0x0400; /* d000-d3ff */
@ -493,8 +577,7 @@ void decocass_state::video_start()
UINT32 decocass_state::screen_update_decocass(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
int scrollx, scrolly_l, scrolly_r;
rectangle clip;
/* THIS CODE SHOULD NOT BE IN SCREEN UPDATE !! */
if (0xc0 != (machine().root_device().ioport("IN2")->read() & 0xc0)) /* coin slots assert an NMI */
m_maincpu->set_input_line(INPUT_LINE_NMI, ASSERT_LINE);
@ -504,6 +587,9 @@ UINT32 decocass_state::screen_update_decocass(screen_device &screen, bitmap_ind1
else if (m_watchdog_count-- > 0)
machine().watchdog_reset();
/* (end) THIS CODE SHOULD NOT BE IN SCREEN UPDATE !! */
#ifdef MAME_DEBUG
{
if (machine().input().code_pressed_once(KEYCODE_I))
@ -525,39 +611,10 @@ UINT32 decocass_state::screen_update_decocass(screen_device &screen, bitmap_ind1
bitmap.fill(0, cliprect);
scrolly_l = m_back_vl_shift;
scrolly_r = 256 - m_back_vr_shift;
scrollx = 256 - m_back_h_shift;
if (0 == (m_mode_set & 0x02))
scrollx += 256;
#if 0
/* this is wrong */
if (0 != m_back_h_shift && 0 == ((m_mode_set ^ (m_mode_set >> 1)) & 1))
scrollx += 256;
#endif
if (0 == (m_mode_set & 0x04))
scrolly_r += 256;
else
scrolly_l += 256;
m_bg_tilemap_l->set_scrollx(0, scrollx);
m_bg_tilemap_l->set_scrolly(0, scrolly_l);
m_bg_tilemap_r->set_scrollx(0, scrollx);
m_bg_tilemap_r->set_scrolly(0, scrolly_r);
if (m_mode_set & 0x08) /* bkg_ena on ? */
{
clip = m_bg_tilemap_l_clip;
clip &= cliprect;
m_bg_tilemap_l->draw(bitmap, clip, TILEMAP_DRAW_OPAQUE, 0);
clip = m_bg_tilemap_r_clip;
clip &= cliprect;
m_bg_tilemap_r->draw(bitmap, clip, TILEMAP_DRAW_OPAQUE, 0);
draw_edge(bitmap,cliprect,0,true);
draw_edge(bitmap,cliprect,1,true);
}
if (m_mode_set & 0x20)
@ -571,13 +628,8 @@ UINT32 decocass_state::screen_update_decocass(screen_device &screen, bitmap_ind1
draw_center(bitmap, cliprect);
if (m_mode_set & 0x08) /* bkg_ena on ? */
{
clip = m_bg_tilemap_l_clip;
clip &= cliprect;
m_bg_tilemap_l->draw(bitmap, clip, 0, 0);
clip = m_bg_tilemap_r_clip;
clip &= cliprect;
m_bg_tilemap_r->draw(bitmap, clip, 0, 0);
draw_edge(bitmap,cliprect,0,false);
draw_edge(bitmap,cliprect,1,false);
}
}
m_fg_tilemap->draw(bitmap, cliprect, 0, 0);