sliding movement on collision detection
Monday, April 9, 2012 - 23:12
May I know how it works? I believe this is where the movement and collision detection happens - http://d.pr/gnQM
I have an idea how it works though - it looks like:
1. your not doing timed-based movement, but rather pixel by pixel.
2. until "speed" or "distance" is met - you will loop through x and y player position and increment it every loop depending on a set of condition. the function finishes with the x and y position incremented for the current frame
I'm particularly interseted in the sliding - absolute stop is pretty much straightforward. Also my difficulty problably also lies because on my game i'm doing timed-based movement.
Can you explain how your sliding and movement technically works please?
This function is a specific case. In my game movement happens in 8 direction.
When this function is called, step_x and step_y will be -1, 0, or 1. These basically define which direction the movement happens. dist is the total desired movement distance.
For the entire desired distance I move 1 unit (sort of like map pixels) at a time. I check to see if the next coordinate is open, and move one unit if it is.
If the next coordinate is blocked, and I'm moving diagonally, I try "sliding" along the wall. This means instead of checking in the (step_x,step_y) direction, I check (step_x,0) and (0,step_y) to see if those spaces are open. If so, just move in either X or Y instead of both.
TL;DR: if I can't move in the desired X,Y direction, try moving in just X or just Y.
In a time-based game, your Distance input will be variable based on delta_time since the last frame. That will be calculated before calling a function like this.
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More thoughts:
This function returns False if it wasn't able to move the full distance. The calling code will change the entity's state from Running to Standing when this function returns false.