In which John learns about the playfield hardware and sprite priorities

bun.c

@@ -310,6 +310,13 @@ void calculateBunPositions(
 
     bunPositions[current][0] = x;
     bunPositions[current][1] = y;
+
+    // for the blitter video
+    /*
+    if (frame == 0) {
+      printf("%d,%d\n", bunPositions[current][0], bunPositions[current][1]);
+    }
+    */
   }
 }
 

main.c

@@ -27,6 +27,9 @@ extern struct CIA far ciaa;
 #define SCRATCH_AREA_HEIGHT_ROWS (34)
 #define SCRATCH_AREA_MEMORY_SIZE (SCRATCH_AREA_WIDTH_BYTES * SCRATCH_AREA_HEIGHT_ROWS)
 
+// change to 0 to not render sprites
+#define RENDER_SPRITES (1)
+
 volatile short *dbg = (volatile short *)0x100;
 
 unsigned char *scratchArea;
@@ -143,6 +146,7 @@ int main(void) {
   *(currentCopperlist++) = custom_color + 4;
   *(currentCopperlist++) = 0xfff;
 
+  if (RENDER_SPRITES) {
     for (i = 0; i < 8; ++i) {
       spriteDataPointer = (uint32_t)&SpriteData;
       spriteDataPointer += ((256 + 2) * 4) * i;
@@ -153,11 +157,16 @@ int main(void) {
       *(currentCopperlist++) = custom_sprite + 2 + i * 4;
       *(currentCopperlist++) = (spriteDataPointer & 0xffff);
     }
+  } else {
+    printf("Skipping render\n");
+    currentCopperlist = setUpEmptySpritesInCopperlist(currentCopperlist);
+  }
 
   *(currentCopperlist++) = custom_color;
   *(currentCopperlist++) = 0x3a6;
 
   for (y = 0; y < 256; ++y) {
+    if (RENDER_SPRITES) {
       for (i = 0; i < 8; ++i) {
         // set sprite color
         *(currentCopperlist++) = custom_color + 32 + (
@@ -176,6 +185,9 @@ int main(void) {
         *(currentCopperlist++) = custom_sprite_control + i * 8 + 2;
         *(currentCopperlist++) = *(currentSpriteCopperlist++);
       }
+    } else {
+      printf("Skipping render\n");
+    }
 
     for (i = 3; i < 8; ++i) {
       *(currentCopperlist++) = custom_color + (i * 2);
@@ -188,6 +200,19 @@ int main(void) {
 
   endCopperlist(currentCopperlist);
 
+  /*
+  copperlist debugging
+  for (i = 0; i < 20; ++i) {
+    printf(
+      "%x %x %x %x\n",
+      *(copperlist + (i * 4)),
+      *(copperlist + (i * 4) + 1),
+      *(copperlist + (i * 4) + 2),
+      *(copperlist + (i * 4) + 3)
+    );
+  }
+  */
+
   takeOverSystem();
 
   setCopperlist(copperlist);

system/system.s

@@ -360,7 +360,8 @@ _setUpDisplay:
     MOVE.W D0,bplcon0(A1)
 
     MOVE.W #0,bplcon1(A1)
-    MOVE.W #0,bplcon2(A1)
+    ; sprites always on top
+    MOVE.W #$0020,bplcon2(A1)
     MOVE.W #0,bpl1mod(A1)
     MOVE.W #0,bpl2mod(A1)
     MOVE.W #$2c81,diwstrt(A1)