From 3a42da655bf235e48edbf472a98d40b8dd0817a1 Mon Sep 17 00:00:00 2001
From: John Bintz <hello@theindustriousrabbit.com>
Date: Thu, 12 Sep 2024 08:26:53 -0400
Subject: [PATCH] In which John learns about the playfield hardware and sprite
 priorities

---
 bun.c           |   7 +++++
 main            | Bin 61004 -> 61040 bytes
 main.c          |  69 +++++++++++++++++++++++++++++++++---------------
 system/system.s |   3 ++-
 4 files changed, 56 insertions(+), 23 deletions(-)

diff --git a/bun.c b/bun.c
index 7028730..a2b9feb 100644
--- a/bun.c
+++ b/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]);
+    }
+    */
   }
 }
 
diff --git a/main b/main
index 46b75975c97dffaeb387327b456818bcf6f3f508..295416bc918bc4c5ba51286550cb95f6cfae8589 100755
GIT binary patch
delta 2825
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diff --git a/main.c b/main.c
index 721dcf7..25e9773 100644
--- a/main.c
+++ b/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;
@@ -143,38 +146,47 @@ int main(void) {
   *(currentCopperlist++) = custom_color + 4;
   *(currentCopperlist++) = 0xfff;
 
-  for (i = 0; i < 8; ++i) {
-    spriteDataPointer = (uint32_t)&SpriteData;
-    spriteDataPointer += ((256 + 2) * 4) * i;
+  if (RENDER_SPRITES) {
+    for (i = 0; i < 8; ++i) {
+      spriteDataPointer = (uint32_t)&SpriteData;
+      spriteDataPointer += ((256 + 2) * 4) * i;
 
-    *(currentCopperlist++) = custom_sprite + i * 4;
-    *(currentCopperlist++) = (spriteDataPointer >> 16);
+      *(currentCopperlist++) = custom_sprite + i * 4;
+      *(currentCopperlist++) = (spriteDataPointer >> 16);
 
-    *(currentCopperlist++) = custom_sprite + 2 + i * 4;
-    *(currentCopperlist++) = (spriteDataPointer & 0xffff);
+      *(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) {
-    for (i = 0; i < 8; ++i) {
-      // set sprite color
-      *(currentCopperlist++) = custom_color + 32 + (
-        // sprite color group
-        (i / 2) * 4 +
-        // 0 is transparent
-        1 +
-        i % 2
-      ) * 2;
-      *(currentCopperlist++) = *(currentSpriteCopperlist++);
+    if (RENDER_SPRITES) {
+      for (i = 0; i < 8; ++i) {
+        // set sprite color
+        *(currentCopperlist++) = custom_color + 32 + (
+          // sprite color group
+          (i / 2) * 4 +
+          // 0 is transparent
+          1 +
+          i % 2
+        ) * 2;
+        *(currentCopperlist++) = *(currentSpriteCopperlist++);
 
-      // set sprite position
-      *(currentCopperlist++) = custom_sprite_control + i * 8;
-      *(currentCopperlist++) = *(currentSpriteCopperlist++);
+        // set sprite position
+        *(currentCopperlist++) = custom_sprite_control + i * 8;
+        *(currentCopperlist++) = *(currentSpriteCopperlist++);
 
-      *(currentCopperlist++) = custom_sprite_control + i * 8 + 2;
-      *(currentCopperlist++) = *(currentSpriteCopperlist++);
+        *(currentCopperlist++) = custom_sprite_control + i * 8 + 2;
+        *(currentCopperlist++) = *(currentSpriteCopperlist++);
+      }
+    } else {
+      printf("Skipping render\n");
     }
 
     for (i = 3; i < 8; ++i) {
@@ -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);
diff --git a/system/system.s b/system/system.s
index 078b8c7..34d869d 100644
--- a/system/system.s
+++ b/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)