Added new background visuals

include/affine_background.h

@@ -9,6 +9,7 @@
 #define AFFINE_BG_PB (PAL_ROW_LEN * 15) // This isn't really a palette bank, just the starting index of the palette
 
 void affine_background_init();
+void affine_background_hblank();
 void affine_background_update();
 void affine_background_set_color(COLOR color);
 // Must be called with an array of size at least  AFFINE_BG_PAL_LEN

source/affine_background.c

@@ -5,6 +5,7 @@
 
 BG_AFFINE bgaff;
 AFF_SRC_EX asx = {32<<8, 64<<8, 120, 80, 0x0100, 0x0100, 0};
+static uint timer = 0;
 
 void affine_background_init()
 {
@@ -15,22 +16,26 @@ void affine_background_init()
     bgaff = bg_aff_default;
 }
 
-void affine_background_update()
+void affine_background_hblank()
 {
-    static uint timer = 0;
-    timer++;
+    const s32 timer_s32 = timer << 8;
+    const s32 vcount_s32 = REG_VCOUNT << 8;
+    const s16 vcount_s16 = REG_VCOUNT;
+
+    asx.scr_y = vcount_s16 - 128; // 128 on x and y is an offset used to center the rotation
+    asx.scr_x = 128;
+    asx.tex_x = lu_sin(timer_s32 + vcount_s32) + timer / 8;
+    asx.alpha = (vcount_s32 + timer_s32) / 8;
     
-    // These values are not permament, just the current configuration for the affine background
-    asx.tex_x += 5;
-    asx.tex_y += 12;
-    asx.sx = (lu_sin(timer * 100)) >> 8; // Scale the sine value to fit in a s16
-    asx.sx += 256; // Add 256 to the sine value to make it positive
-    asx.sy = (lu_sin(timer * 100 + 0x4000)) >> 8; // Scale the sine value to fit in a s16
-    asx.sy += 256; // Add 256 to the sine value to make it positive
     bg_rotscale_ex(&bgaff, &asx);
     REG_BG_AFFINE[2] = bgaff;
 }
 
+void affine_background_update()
+{
+    timer++;
+}
+
 void affine_background_set_color(COLOR color)
 {
     memcpy16(&pal_bg_mem[AFFINE_BG_PB], affine_background_gfxPal, AFFINE_BG_PAL_LEN);

source/main.c

@@ -22,6 +22,7 @@ void init()
 {
     irq_init(NULL);
     irq_add(II_VBLANK, mmVBlank);
+    irq_add(II_HBLANK, affine_background_hblank);
 
     // Initialize maxmod
     mmInitDefault((mm_addr)soundbank_bin, 12);