43 lines
884 B
Plaintext
43 lines
884 B
Plaintext
// Pick frame of animation from an instance.
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//
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// This function assumes that the uniform header has been loaded,
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// and that `InstanceInput` contains a field `texture_index`
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fn animate(instance: InstanceInput, age: f32) -> u32 {
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let idx = instance.texture_index;
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let len = sprites.data[idx].frame_count;
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let rep = sprites.data[idx].repeatmode;
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let fps = sprites.data[idx].fps;
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var frame: u32 = u32(0);
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// Once
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if rep == u32(1) {
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frame = u32(min(
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age / fps,
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f32(len) - 1.0
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));
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// Reverse
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} else if rep == u32(2) {
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let x = age / fps;
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let m = f32(len) * 2.0 - 1.0;
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// x fmod m
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frame = u32(x - floor(x / m) * m);
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if frame >= len {
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frame = len + len - frame - u32(1);
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}
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// Repeat (default)
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} else {
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let x = age / fps;
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let m = f32(len);
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// x fmod m
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frame = u32(x - floor(x / m) * m);
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}
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return frame + sprites.data[idx].first_frame;
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} |