SPG:Underwater
From Sonic Retro
Sonic Physics Guide |
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Collision |
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Physics |
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Gameplay |
Presentation |
Special |
Notes:
- The research applies to all four of the Sega Mega Drive games and Sonic CD.
- When Sonic is underwater he moves much more slowly, but otherwise his physics are largely the same. This is achieved mostly by halving the pertinent variables, but some, like gravity and initial jump velocity, are not exactly half.
Contents
Underwater Constants
acceleration_speed: 0.0234375 (half of 0.046875) deceleration_speed: 0.25 (half of 0.5) friction_speed: 0.0234375 (half of 0.046875) top_speed: 3 (half of 6) air_acceleration_speed: 0.046875 (half of 0.09375) roll_friction_speed: 0.01171875 (half of 0.0234375) roll_deceleration_speed: 0.125 (unchanged)
gravity_force: 0.0625 (instead of 0.21875) jump_force: 3.5 (3 for knuckles) (instead of 6.5 (6 for knuckles)) jump_release: -2 (instead of -4)
Getting Hit
When getting hit underwater, the Player will fly back with an X Speed of 1 (or -1) and a Y Speed of -2, half that of normal.
Bubbles
When the Player gets a bubble underwater, their X Speed and Y Speed are both set to 0.
Entry & Exit
When the Player enters the water, their X Speed is multiplied by 0.5 and their Y Speed is multiplied by 0.25 (this occurs after gravity_force is added to Y Speed). Conversely, when the Player exits the water, their Y Speed is doubled (after water gravity_force has been added), (however, X Speed is not affected when leaving the water).
Drowning
When the Player drowns, their X Speed and Y Speed are both set to 0, and the gravity_force remains set to the lower water gravity.
Speed Shoes
When in possession of Speed Shoes, but also underwater, the underwater variables take over, effectively nullifying the Speed Shoes altogether. No calculations, such as multiplying by 0.5, take place.
Animation Speeds
Being submerged doesn't affect the speed of the Player's animations at all. Variable Speed Animations will be attenuated by the same proportion automatically.