Animating Sprites

The Untold Engine supports sprites animation. The engine represents a sprite animation as a U4DEngine::U4DSpriteAnimation object.

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Pre-requisite

A U4DSpriteAnimation object requires that you have successfully created a U4DEngine::U4DSprite object with its corresponding spritesheet, as shown in lines 1-6. If you need a refresher, please see the following article.

//Line 1. create a a sprite loader object
U4DEngine::U4DSpriteLoader *spriteLoader=new U4DEngine::U4DSpriteLoader();

//Line 2. load the sprite information into the loader
spriteLoader->loadSpritesAssetFile("spaceinvaderspritesheet.xml", "spaceinvaderspritesheet.png");

//Line 3. Create a sprite object
U4DEngine::U4DSprite *mySprite=new U4DEngine::U4DSprite(spriteLoader);

//Line 4. Set the sprite to render
mySprite->setSprite("spaceinvaderoctopus1.png");

//Line 5.Add it to the world
addChild(mySprite,-2);

//Line 6. translate the sprite
mySprite->translateTo(0.0,0.5,0.0);

Step 1. Load animation sprites

Once a spritesheet has been loaded into a U4DEngine::U4DSpriteLoader and a U4DEngine::U4DSprite has been created, you must load the sprites that will be part of the animation into a U4DEngine::SPRITEANIMATIONDATA structure, as shown in line 7.

//Line 7. Load all the sprite animation data into the structure
U4DEngine::SPRITEANIMATIONDATA spriteAnimationData;

spriteAnimationData.animationSprites.push_back("spaceinvaderoctopus1.png");
spriteAnimationData.animationSprites.push_back("spaceinvaderoctopus2.png");

//Line 8. set a delay for the animation
spriteAnimationData.delay=0.2;

In this example, the sprites that will be part of the animation are:

  • spaceinvaderoctopus1.png
  • spaceinvaderoctopus2.png

These sprites are highlighted in the spritesheet below:

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Line 8 provides a delay interval for the animation. Basically, it determines how fast to play the animation.

Create Sprite Animation Object

Once the U4DEngine::SPRITEANIMATIONDATA structure has the corresponding sprites and a delay value, a U4DEngine::U4DSpriteAnimation object is created using the structure and sprite object as parameters. See line 9.

Finally, the sprite animation object is started by calling its play() method, as shown in line 10.

//Line 9. create a sprite animation object
U4DEngine::U4DSpriteAnimation *spriteAnim=new U4DEngine::U4DSpriteAnimation(mySprite,spriteAnimationData);

//Line 10. Play the sprite animation
spriteAnim->play();

Here is the result:

image