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gaplus : Fixed displaying of starfield (#6746)

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* gaplus : Fixed star behavior with reference to PCB.
- Scrolling speed and direction (Testers-00434)
- Clipping the Display Area (Testers-07663)
- Modified to use sprite color instead of text color with refer to the PCB
- Added blinking when the movement of the star changes
This commit is contained in:
sasuke-arcade 2020-05-27 08:56:49 +09:00 committed by GitHub
parent 1e70d64d56
commit f68e9f01ea
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 45 additions and 21 deletions
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1
src/mame/includes/gaplus.h
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@ -109,6 +109,7 @@ protected:
tilemap_t *m_bg_tilemap;
uint8_t m_starfield_control[4];
int m_total_stars;
int m_starfield_framecount;
struct star m_stars[MAX_STARS];
uint8_t m_main_irq_mask;
uint8_t m_sub_irq_mask;

65
src/mame/video/gaplus.cpp
View File

@ -114,9 +114,10 @@ TILE_GET_INFO_MEMBER(gaplus_base_state::get_tile_info)
***************************************************************************/
/* starfield speed constants (bigger = faster) */
#define SPEED_1 0.5f
#define SPEED_2 1.0f
#define SPEED_3 2.0f
#define SPEED_1 1.0f
#define SPEED_2 2.0f
#define SPEED_3 3.0f
#define STARFIELD_CLIPPING_X 16
void gaplus_base_state::starfield_init()
{
@ -127,13 +128,14 @@ void gaplus_base_state::starfield_init()
const int height = m_screen->height();
m_total_stars = 0;
m_starfield_framecount = 0;
/* precalculate the star background */
/* this comes from the Galaxian hardware, Gaplus is probably different */
for (int y = 0; y < height; y++)
{
for (int x = width * 2 - 1; x >= 0; x--)
for (int x = width - (STARFIELD_CLIPPING_X * 2) - 1; x >= 0; x--)
{
generator <<= 1;
const int bit1 = (~generator >> 17) & 1;
@ -143,12 +145,27 @@ void gaplus_base_state::starfield_init()
if (BIT(~generator, 16) && (generator & 0xff) == 0xff)
{
const int color = ~(generator >> 8) & 0x3f;
const int color = (~(generator >> 8)) % 7 + 1;
int color_base = 0;
/* A guess based on comparison with PCB video output */
switch (set)
{
case 0:
color_base = 0x250;
break;
case 1:
color_base = 0x230;
break;
case 2:
color_base = 0x210;
break;
}
if (color && m_total_stars < MAX_STARS)
{
m_stars[m_total_stars].x = x;
m_stars[m_total_stars].x = x + STARFIELD_CLIPPING_X;
m_stars[m_total_stars].y = y;
m_stars[m_total_stars].col = color;
m_stars[m_total_stars].col = color_base + color;
m_stars[m_total_stars].set = set++;
if (set == 3)
@ -178,6 +195,7 @@ void gaplus_base_state::video_start()
starfield_init();
save_item(NAME(m_starfield_control));
save_item(NAME(m_starfield_framecount));
for (int i = 0; i < MAX_STARS; i++)
{
@ -229,6 +247,13 @@ void gaplus_base_state::starfield_render(bitmap_ind16 &bitmap)
int x = m_stars[i].x;
int y = m_stars[i].y;
/* Some stars in the second tier will flash erratically while changing their movements. */
if (m_stars[i].set == 1 && m_starfield_control[2] != 0x85 && i % 2 == 0)
{
int bit = BIT(m_starfield_framecount + i, 3) ? 1 : 2;
if (BIT(m_starfield_framecount + i, bit)) { continue; }
}
if (x >= 0 && x < width && y >= 0 && y < height)
{
bitmap.pix16(y, x) = m_stars[i].col;
@ -319,6 +344,8 @@ WRITE_LINE_MEMBER(gaplus_base_state::screen_vblank)/* update starfields */
int width = m_screen->width();
int height = m_screen->height();
m_starfield_framecount ++;
/* check if we're running */
if ( ( m_starfield_control[0] & 1 ) == 0 )
return;
@ -330,21 +357,17 @@ WRITE_LINE_MEMBER(gaplus_base_state::screen_vblank)/* update starfields */
/* stand still */
break;
case 0x85:
case 0x86:
/* scroll down (speed 1) */
stars[i].x += SPEED_1;
break;
case 0x85:
case 0x06:
/* scroll down (speed 2) */
stars[i].x += SPEED_2;
break;
case 0x06:
/* scroll down (speed 3) */
stars[i].x += SPEED_3;
break;
case 0x80:
/* scroll up (speed 1) */
stars[i].x -= SPEED_1;
@ -362,21 +385,21 @@ WRITE_LINE_MEMBER(gaplus_base_state::screen_vblank)/* update starfields */
case 0x9f:
/* scroll left (speed 2) */
stars[i].y += SPEED_2;
stars[i].y += SPEED_3;
break;
case 0xaf:
/* scroll left (speed 1) */
stars[i].y += SPEED_1;
/* scroll right (speed 1) */
stars[i].y -= SPEED_3;
break;
}
/* wrap */
if ( stars[i].x < 0 )
stars[i].x = ( float )( width*2 ) + stars[i].x;
if ( stars[i].x < STARFIELD_CLIPPING_X )
stars[i].x = ( float )( width-STARFIELD_CLIPPING_X*2) + stars[i].x;
if ( stars[i].x >= ( float )( width*2 ) )
stars[i].x -= ( float )( width*2 );
if ( stars[i].x >= ( float )( width-STARFIELD_CLIPPING_X) )
stars[i].x -= ( float )( width-STARFIELD_CLIPPING_X*2);
if ( stars[i].y < 0 )
stars[i].y = ( float )( height ) + stars[i].y;