When you start your first jump, your current height tile will be saved. Upon landing it will apply damage based on this initial height.
This Mod disables Fall Damage when Double-Jumping right before hitting the ground
Edit: This bug has been fixed in Terraria v1.0.3, but Diede was first!
Player.cs
for (int num28 = 0; num28 < 10; num28++)
this.fallStart = (int) (this.position.Y / 16);
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