constrained parallax scrolling

diff --git a/src/data.s b/src/data.s
index c36ae73..81ebd47 100644 (file)
--- a/src/data.s
+++ b/src/data.s
@@ -12,6 +12,8 @@
        .globl simbabg_cmap_end
        .globl simbabg_tmap
        .globl simbabg_tmap_end
+       .globl simbafg_data
+       .globl simbafg_data_end
        .globl simbafg_cmap
        .globl simbafg_cmap_end
        .globl simbafg_tmap

diff --git a/src/part_dna.c b/src/part_dna.c
index 2b5b6aa..af6bc98 100644 (file)
--- a/src/part_dna.c
+++ b/src/part_dna.c
@@ -36,6 +36,21 @@ void dna_init(void)
 
 void dna_start(void)
 {
+       short i;
+
+       /* setup tilemaps */
+       vdp_setup_addr(VDP_VRAM, 0xc000);       /* nametable A */
+       for(i=0; i<2048; i++) {
+               VDP_DATA = 0;
+       }
+       vdp_setup_addr(VDP_VRAM, 0xe000);       /* nametable B */
+       for(i=0; i<2048; i++) {
+               VDP_DATA = 0;
+       }
+
+       vdp_setup_addr(VDP_VRAM, 0xf000);       /* hscroll table is at f000, see vdp.S */
+       VDP_DATA = 0;
+       VDP_DATA = 0;
 }
 
 void dna_update(void)

diff --git a/src/part_simba.c b/src/part_simba.c
index a10e5fd..ea6f3ae 100644 (file)
--- a/src/part_simba.c
+++ b/src/part_simba.c
@@ -3,12 +3,19 @@
 #include "vdp.h"
 #include "pad.h"
 #include "parts.h"
+#include "debug.h"
+
+#define BGTILES_OFFS           1
+#define FGTILES_OFFS           4
 
 extern uint16_t simbabg_data[], simbabg_data_end[];
 extern unsigned char simbabg_cmap[], simbabg_cmap_end[];
 extern uint16_t simbabg_tmap[], simbabg_tmap_end[];
+extern uint16_t simbafg_data[], simbafg_data_end[];
+extern unsigned char simbafg_cmap[], simbafg_cmap_end[];
+extern uint16_t simbafg_tmap[], simbafg_tmap_end[];
 
-static int scroll;
+static short scroll;
 
 void simba_init(void)
 {
@@ -16,10 +23,16 @@ void simba_init(void)
 
        /* upload tiles */
        src = simbabg_data;
-       vdp_setup_addr(VDP_VRAM, 32);   /* start from tile 1 32 bytes on */
+       vdp_setup_addr(VDP_VRAM, BGTILES_OFFS * 32);    /* start from tile 1 32 bytes on */
        while(src < simbabg_data_end) {
                VDP_DATA = *src++;
        }
+
+       src = simbafg_data;
+       vdp_setup_addr(VDP_VRAM, FGTILES_OFFS * 32);
+       while(src < simbafg_data_end) {
+               VDP_DATA = *src++;
+       }
 }
 
 void simba_start(void)
@@ -29,10 +42,15 @@ void simba_start(void)
        unsigned char *cptr;
 
        /* setup tilemaps */
+       src = simbafg_tmap;
+       vdp_setup_addr(VDP_VRAM, 0xc000);       /* nametable A */
+       while(src < simbafg_tmap_end) {
+               VDP_DATA = VDP_TILENAME(*src++ + FGTILES_OFFS, 3, 0);
+       }
        src = simbabg_tmap;
        vdp_setup_addr(VDP_VRAM, 0xe000);       /* nametable B */
        while(src < simbabg_tmap_end) {
-               VDP_DATA = VDP_TILENAME(*src++ + 1, 2, 0);
+               VDP_DATA = VDP_TILENAME(*src++ + BGTILES_OFFS, 2, 0);
        }
 
        /* setup colormaps */
@@ -41,23 +59,33 @@ void simba_start(void)
                vdp_setcolor(2, i, cptr[0] >> 4, cptr[1] >> 4, cptr[2] >> 4);
                cptr += 3;
        }
+       cptr = simbafg_cmap;
+       for(i=0; i<16; i++) {
+               vdp_setcolor(3, i, cptr[0] >> 4, cptr[1] >> 4, cptr[2] >> 4);
+               cptr += 3;
+       }
 
        /* set scrolling to whole screen */
        vdp_setreg(VDP_REG_MODE3, 0);
+       scroll = 0;
+       vdp_setup_addr(VDP_VRAM, 0xf000);       /* hscroll table is at f000, see vdp.S */
+       VDP_DATA = 0;
+       VDP_DATA = 0;
 }
 
 void simba_update(void)
 {
        if(bnstate & PAD_LEFT) {
-               if(scroll > 0) scroll--;
+               if(scroll < 0) scroll++;
        } else if(bnstate & PAD_RIGHT) {
-               if(scroll < 511) scroll++;
+               if(scroll > -192) scroll--;
        }
+       dbgval[0] = scroll;
 }
 
 void simba_vblank(void)
 {
        vdp_setup_addr(VDP_VRAM, 0xf000);       /* hscroll table is at f000, see vdp.S */
-       VDP_DATA = 0;
        VDP_DATA = scroll;
+       VDP_DATA = scroll >> 1;
 }