39 lines
1.1 KiB
Lua
39 lines
1.1 KiB
Lua
local inspect = require('inspect')
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local phys = {
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tau = 2 * math.pi
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}
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-- returns true if the two actors intersect
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function phys.intersects(actor1, actor2)
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return (actor1.x - actor2.x) ^ 2 + (actor1.y - actor2.y) ^ 2 <= (actor1.radius + actor2.radius) ^ 2
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end
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-- updates the actor's location by applying the passage of time
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-- TODO spin
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function phys.update(actor, dt)
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assert(actor.speed >= 0)
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local dv = actor.speed * dt
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actor.x = actor.x + math.cos(actor.angle) * dv
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actor.y = actor.y + math.sin(actor.angle) * dv
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end
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function phys.rotate(actor, angle)
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actor.facing = (actor.facing + angle) % phys.tau
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end
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function phys.apply(actor, force)
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local ax = math.cos(actor.angle) * actor.speed
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local ay = math.sin(actor.angle) * actor.speed
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local fx = math.cos(force.angle) * force.speed
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local fy = math.sin(force.angle) * force.speed
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local x = ax + fx
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local y = ay + fy
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local speed = math.sqrt(x ^ 2 + y ^ 2)
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local angle = math.atan2(y, x) % phys.tau
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actor.speed = speed
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actor.angle = angle
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end
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return phys
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