Programming 2D Games

The official forum for "Programming 2D Games" the book by: Charles Kelly

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PostPosted: Wed Dec 27, 2017 6:59 pm 

Joined: Thu Oct 05, 2017 6:53 am
Posts: 15
Unless I'm misunderstanding, it appears to me that there isn't a way to have an Image where its 'startFrame' is larger than its 'endFrame'

I have some use cases where I'm interested in an animation being able to play in either direction

To make this happen, I changed the Image::update() function to this:
void Image::update(float frameTime)
    if (endFrame != startFrame)          // if animated sprite
        animTimer += frameTime;             // total elapsed time
        if (animTimer > frameDelay)
            animTimer -= frameDelay;
            if (startFrame < endFrame)
            if ((currentFrame > endFrame && startFrame < endFrame) ||
                (currentFrame < endFrame && startFrame > endFrame))
                if(loop == true)            // if looping animation
                    currentFrame = startFrame;
                else                        // not looping animation
                    currentFrame = endFrame;
                    animComplete = true;    // animation complete
            setRect();                      // set spriteData.rect

And I added this simple helper function to image.h to allow easily reversing the animation:
// Reverse animation frames
virtual void reverseAnimation() { std::swap(startFrame, endFrame); }

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