From Sonic Retro
Shown below are the speeds of the animations featured in the Sonic games. Such information can be used to replicate accurate animations in a fangame engine.
Every sprite subimage in this animation lasts for 24 frames. Sonic stays still for 288 frames (the subimage occurs 12 times in the animation code) before entering the waiting subimages of the idle animation. When the waiting portion begins, Sonic enters a subimage for 24 frames, then has his eyes wide open for 72 frames. Afterwards, he will alternate between two subimages every 24 frames, making Sonic appear to tap his foot on the ground. This will loop until the player takes action.
Every sprite subimage in this animation lasts for 6 frames. Sonic stays still for 180 frames (the subimage occurs 30 times in the animation code) before entering the first set of waiting subimages of the idle animation. He then blinks, which lasts for 6 frames, then has his eyes wide open for 30 frames. Afterwards, he will alternate between two subimages every 18 frames, making Sonic appear to tap his foot on the ground. This will loop until the player takes action.
Should the player NOT take action after Sonic taps his foot 3 times (126 frames) (Note: the animation starts with Sonic's foot down and ends with it pointing upwards), he will then look down at his wrist(watch?) for 60 frames, then resume tapping his foot. This foot-tapping/wristwatch sequence will continue 3 more times (204 frames/sequence*4=816 total frames). Afterwards, if no action is taken at this point, Sonic will enter a new animation where he lies down on the floor. It takes 6 frames for him to drop to the ground. He then enters a final alternating sequence tapping his finger against his shoe. Both subimages in this sequence last for 18 frames each.
Every sprite subimage in this animation lasts for 6 frames.
Walking and Running
When Sonic is walking or running, the animation waits 8-absolute(Ground speed) frames before advancing to the next subimage. This is the same in Sonic 1, 2 and 3. This remains even when at full speed (spinning feet), or faster. Now, if the result of 8 minus the ground speed means it will wait less than one step before advancing a frame, it is just set to 1. So, to properly emulate this in your engine, here is some pseudo-code
//The frame-rate is set to 8 minus the absolute value of ground speed. frame_duration = max(8-abs(g_speed), 1); //Frame-rate minimum is capped at 1.
The spinning animation for jumping/rolling works slightly differently. The animation waits
frames before advancing to the next subimage, instead of 8. When rolling along the ground, the speed of the animation will change with Sonic's ground speed. When rolling in the air or jumping, the animation speed will remain constant, due to the fact that ground speed does NOT update in the air. In other words, the animation remains the speed it was when you left the ground until you land.
The animation waits 32 frames before advancing to the next subimage when pushing. This remains true in all games.
While balancing, the animation waits 16 frames before advancing to the next subimage.
In Sonic 2 each of the 3 balancing animations have different animation speeds.
The facing forward balance animation waits 10 frames before advancing to the next subimage.
The backwards balance animation waits 20 frames before advancing to the next subimage.
And the last balance animation waits 4 frames before advancing to the next subimage.
In Sonic 3 there are only 2 balancing animations, the one when you're at the edge, and the one when you're further down the edge.
The first one waits 8 frames before advancing to the next subimage.
And the second one waits 6 frames before advancing to the next subimage.
In Sonic 1, the animation waits 8 frames before advancing to the next subimage while braking. It will continue to loop between the two subimages until Sonic has stopped. In Sonic 2 and Sonic 3K, the animation will stop when it finishes, instead of looping.
The spindash animation itself waits 1 frame to advance a subimage.
When a button is pressed to charge up the spindash, the subimage is set to 1 (therefor resetting it).
Converting The Frame Duration
For programs such as GameMaker or MMF, to display an animation properly without an advances system, you may need the speed of the animation instead of the duration of the frames.
- In GameMaker, the animation speed (image_speed) is how many subimages will be advanced per frame, so a speed of 1 will advance a subimage each frame,and 0.5 will advance a subimage every 2 frames. Although it's better to just set the image_speed like this in the first place.
- To convert a frame duration to a GameMaker image speed, simply divide 1 by it.
//Converts the frame duration into an image_speed compatible value for GameMaker. image_speed = (1/frame_duration);