Sprite Animation Manager

Untitled 2D Sprite Project

1. Ecosystem

• Build system
  • Unix-like platforms (Ubuntu, Gentoo, etc.)
• Targeted on Nintendo 3DS
  • devkitPro 3ds-dev
  • citro2d library

2. Setup

Follow the guidelines from the devkitPro website

3. Basic Sprite Animation

master branch #2dce989

A simple basic animation using the citro2d library. The 3DS models and system versions we tesetd are:

Model	System version
New Nintendo 3DS LL	Sys 11.14.0-46J

The Citra versions we tested are:

Build	Release version
Citra Canary	1992

Adding sprites

1. Add sprites which you want to animate in the gfx folder.
2. Add sprite names into the sprites.t3s.

• Note: The sprites.t3s file must(?) be included in the gfx folder and the format should be like (need more research):

  --atlas -f rgba8888 -z auto
  frame_00_delay-0.1s.png
  frame_01_delay-0.1s.png
  frame_02_delay-0.1s.png
  frame_03_delay-0.1s.png
  frame_04_delay-0.1s.png
  frame_05_delay-0.1s.png
  frame_06_delay-0.1s.png
  frame_07_delay-0.1s.png
  frame_08_delay-0.1s.png
  frame_09_delay-0.1s.png

1. Load the sprite using C2D_SpriteSheetLoad().

   spriteSheet = C2D_SpriteSheetLoad("romfs:/gfx/sprites.t3x");
   if (spriteSheet == NULL) {
       svcBreak(USERBREAK_PANIC);
   }

Frame rate update

1. Set a desired sprite refresh time (unit: ms)

   static uint64_t sprite_refresh_ms_time = 30;

2. Get a time from the begining of the while loop

   start = osGetTime();

3. Calculate the elaspsed time before drawing the sprite

   stop = osGetTime();
   ms_time_elapsed += (stop - start);

4. Check that the elapsed time is greater than or equal to the deisred sprite refresh time (sprite_refresh_ms_time)

   if (ms_time_elapsed >= sprite_refresh_ms_time) {
       ms_time_elapsed -= sprite_refresh_ms_time;
       
       /*Draw some sprites*/
    
       // Making an animation loop sprite counter
       // This will indecate 0, 1, 2, ... 13, 0, 1, 2, ... 13, 0, ... sequentially.
       current_frame_index = (current_frame_index + 1) % MAX_SPRITES;
       // Render the scene
       C3D_FrameBegin(C3D_FRAME_SYNCDRAW);
       C2D_TargetClear(top, C2D_Color32f(0.0f, 0.0f, 0.0f, 1.0f));
       C2D_SceneBegin(top);
       
       // Draw the player animation
       C2D_DrawSprite(&reimu_sprite[current_frame_index]);
   }

Result

Reimu sprite animation (idle) (Animation source: Touhou 13.5: Shinkirou - Hopeless Masquerade)

Limitations

• Wrong frame rate indication in Citra

4. Sprite Animation Manager

Implementation (TODO)

Basic features

• [x] Load sprites
• [x] Set sprite origin, position, rotation

Animation state controller

• [ ] Play loop or once
• [ ] State machine

Sprite pose manager

• [ ] AABB detection
• [ ] Collison activation
• [ ] Gravity activation
• [ ] x or y direction lock

The 3DS models and system versions we tesetd are:

Model	System version
New Nintendo 3DS LL	Sys 11.14.0-46J

The Citra versions we tested are:

Build	Release version
Citra Canary	1992

Assumptions

1. Object is a 2D object which contains sprites, a pivot, a position, and a roation.
2. Object can be affected by a gravity or not.

Basic features

In sprite_animation_manager.h, there is a initialize_object() to initialze 2D object. the initialize_object() has lots of initialization features as follows:

• Load spirtes from the file name
• Position
• Pivot point
• Rotation (in radians)
• Animation refresh time

// Set initial values
static object_2d_info_t reimu_object;
static C2D_Sprite reimu_sprite[MAX_SPRITES];
static sprite_pivot_t reimu_pivot = {0.0f, 0.0f};
static sprite_position_t reimu_position = {0.0f, 0.0f};
static float reimu_roation = 0.0f;
static uint64_t sprite_refresh_ms_time = 30;
 
// Load graphics and initialize player sprites
initialize_object(&reimu_object, \
                   reimu_sprite, \
                   "romfs:/gfx/sprites.t3x", \
                   reimu_pivot, \
                   reimu_position, \
                   reimu_roation, \
                   sprite_refresh_ms_time);

After the object initialized, draw sprite using draw_sprite_animation()

// Render the scene
C3D_FrameBegin(C3D_FRAME_SYNCDRAW);
C2D_TargetClear(top, C2D_Color32f(0.0f, 0.0f, 0.0f, 1.0f));
C2D_SceneBegin(top);
draw_sprite_animation(&reimu_object);

When the application ends, any sprites or graphics must be freed.

// Delete graphics
C2D_SpriteSheetFree(reimu_object.spritesheet);

• Note: Using C2D_SpriteSheetFree() to free will be deprecated in the next commit.

A. Other things to do

Found the useful links to make a documentation using doxygen

• Doxygen Basics - Abdullah
• Complete Guide On Using Doxygen To Document C Source Code..!!