From b552e242609a5d3b9debd7927aa9c1c2186ce847 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Sun, 18 Apr 2021 21:01:30 +0200
Subject: Add a bouncing animation for ASCII sprites

---
 src/main.c | 135 +++++++++++++++++++++++++++++++------------------------------
 1 file changed, 69 insertions(+), 66 deletions(-)

diff --git a/src/main.c b/src/main.c
index 17c6654..e39551c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -442,31 +442,41 @@ copy_font_to_tile_memory(Tile *tile) {
     }
 }
 
+static int bouncing_animation[] = {
+    0, 0, 0,
+    0, 0, 0,
+    0, 0, 0,
+    0, 0, 0,
+    1, 1, 1,
+    3, 3, 3,
+    5, 5, 5,
+    5, 5, 5,
+    7, 7, 7,
+    8, 8, 8,
+    7, 7, 7,
+    5, 5, 5,
+    5, 5, 5,
+    3, 3, 3,
+    1, 1, 1,
+    0, 0, 0,
+    0, 0, 0,
+    0, 0, 0,
+    0, 0, 0,
+};
+
+typedef struct FontSprite {
+    int x;
+    int y;
+    int animation_state;
+    u32 tile_index;
+    u32 pal_bank;
+} FontSprite;
+
 int main(void) {
     // Configure the display in mode 0 to show OBJs, where tile memory is
     // sequential.
     DISP_CTRL = DISP_MODE_3 | DISP_OBJ | DISP_OBJ_1D | DISP_BG_2;
 
-    // Create two 4bpp tiles, one filled with color 1 and another with color 2.
-    Tile *tile_mem = &TILE_MEM[4][512];
-    // size_t n_tiles = 8;
-    // u32 colors[] = {
-    //     0x11111111,
-    //     0x22222222,
-    //     0x33333333,
-    //     0x44444444,
-    //     0x55555555,
-    //     0x66666666,
-    //     0x77777777,
-    //     0x88888888,
-    // };
-    // for (size_t j = 0; j < n_tiles; ++j) {
-    //     for (size_t i = j * 8; i < 8 + 8 * j; ++i) {
-    //         tile_mem->data[i] = colors[j];
-    //     }
-    // }
-    copy_font_to_tile_memory(tile_mem);
-
     // Add colors to the sprite color palette. Tiles with color number 0 are
     // treated as transparent.
     PAL_BUFFER_SPRITES[1] = COLOR_WHITE;
@@ -478,82 +488,75 @@ int main(void) {
     PAL_BUFFER_SPRITES[7] = COLOR_CYAN;
     PAL_BUFFER_SPRITES[8] = COLOR_BLUE;
 
-    int x_a = 100;
-    int y_a = 100;
-    int tile_id_a = 512;
-    int x_b = 50;
-    int y_b = 50;
-    int tile_id_b = 513;
-
     // Initialize all attributes by disabling rendering. If we don't do this,
     // glitches may appear.
     for (size_t i = 0; i < 128; ++i) {
         OBJ_ATTR_0(i) = (1 << 9);
     }
 
-    OBJ_ATTR_0(0) = y_a;
-    OBJ_ATTR_1(0) = x_a  | (1 << 14);
-    OBJ_ATTR_2(0) = tile_id_a;
+    size_t initial_tile = 512;
+    Tile *tile_mem = &TILE_MEM[4][initial_tile];
 
-    OBJ_ATTR_0(1) = y_b;
-    OBJ_ATTR_1(1) = x_b;
-    OBJ_ATTR_2(1) = tile_id_b;
+    // Load bd-font as tiles. The full extended ASCII range (256 characters)
+    // will be available as an offset of the initial tile. For example, the
+    // uppercase A letter will be at tile index of 512 + 65.
+    copy_font_to_tile_memory(tile_mem);
 
-    draw_logo();
+    // Initialize character sprites for all font chars.
+    FontSprite font_sprites[256] = {0};
+    size_t x = 49;
+    size_t y = 0;
+    for (size_t i = 0; i < 256; ++i) {
+        font_sprites[i].x = x;
+        font_sprites[i].y = y;
+        font_sprites[i].tile_index = initial_tile + i;
+        font_sprites[i].animation_state = i % 56;
+        if ((i % 16) == 0) {
+            y += 16;
+            x = 49;
+        }
+        x += 8;
+    }
+
+    // Number of characters to become sprites.
+    size_t n_chars = 128;
+    for (size_t i = 0; i < n_chars; ++i) {
+        OBJ_ATTR_0(i) = font_sprites[i].y;
+        OBJ_ATTR_1(i) = font_sprites[i].x;
+        OBJ_ATTR_2(i) = font_sprites[i].tile_index;
+    }
+
+    // draw_logo();
 
     int frame_counter = 0;
-    int active_sprite = 0;
     while(true) {
         wait_vsync();
         poll_keys();
 
         // Toggle frame counter when we press down.
         if (key_pressed(KEY_DOWN) || key_hold(KEY_DOWN)) {
-            if (active_sprite == 0) {
-                y_a += 3;
-            } else {
-                y_b += 3;
-            }
         }
         if (key_pressed(KEY_UP) || key_hold(KEY_UP)) {
-            if (active_sprite == 0) {
-                y_a -= 3;
-            } else {
-                y_b -= 3;
-            }
         }
         if (key_pressed(KEY_LEFT) || key_hold(KEY_LEFT)) {
-            if (active_sprite == 0) {
-                x_a -= 3;
-            } else {
-                x_b -= 3;
-            }
         }
         if (key_pressed(KEY_RIGHT) || key_hold(KEY_RIGHT)) {
-            if (active_sprite == 0) {
-                x_a += 3;
-            } else {
-                x_b += 3;
-            }
         }
         if (key_pressed(KEY_B)) {
-            if (active_sprite == 0) {
-                active_sprite = 1;
-            } else {
-                active_sprite = 0;
-            }
         }
         if (key_pressed(KEY_L)) {
-            OBJ_ATTR_2(0) = OBJ_ATTR_2(0) - 1;
         }
         if (key_pressed(KEY_R)) {
-            OBJ_ATTR_2(0) = OBJ_ATTR_2(0) + 1;
         }
 
-        OBJ_ATTR_0(0) = (OBJ_ATTR_0(0) & ~0xFF)  | (y_a & 0xFF);
-        OBJ_ATTR_1(0) = (OBJ_ATTR_1(0) & ~0x1FF) | (x_a & 0x1FF);
-        OBJ_ATTR_0(1) = (OBJ_ATTR_0(1) & ~0xFF)  | (y_b & 0xFF);
-        OBJ_ATTR_1(1) = (OBJ_ATTR_1(1) & ~0x1FF) | (x_b & 0x1FF);
+        for (size_t i = 0; i < 128; ++i) {
+            int y = font_sprites[i].y;
+            y -= bouncing_animation[font_sprites[i].animation_state++];
+            if (font_sprites[i].animation_state > 56) {
+                font_sprites[i].animation_state = 0;
+            }
+            OBJ_ATTR_0(i) = (OBJ_ATTR_0(i) & ~0xFF)  | (y & 0xFF);
+        }
     };
 
     return 0;
-- 
cgit v1.2.1