Difference between revisions of "BezierCurve:evaluate"

(Make a circle follow a curve)
(Undo revision 27963 by Darkfrei (talk). Mention the control point requirement in the description instead.)
(Tag: Undo)
 
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{{newin|[[0.9.0]]|090|type=function}}
 
{{newin|[[0.9.0]]|090|type=function}}
Evaluate Bézier curve at parameter t. The parameter must be between 0 and 1 (inclusive).
+
Evaluate Bézier curve at parameter t. The parameter must be between 0 and 1 (inclusive) and there must be at least two control points for the curve.
  
This function can be used to move objects along paths or tween parameters. However it should not be used to render the curve, see [[BezierCurve:render]] for that purpose.
+
This function can be used to move objects along paths or tween parameters. However it should not be used to render the curve - see [[BezierCurve:render]] for that purpose.
  
 
== Function ==
 
== Function ==
 
=== Synopsis ===
 
=== Synopsis ===
 
<source lang="lua">
 
<source lang="lua">
x,y = BezierCurve:evaluate(t)
+
x, y = BezierCurve:evaluate( t )
 
</source>
 
</source>
 
=== Arguments ===
 
=== Arguments ===
{{param|number|t|Where to evaluate the curve.}}
+
{{param|number|t|Where to evaluate the curve. Must be between 0 and 1.}}
 
=== Returns ===
 
=== Returns ===
 
{{param|number|x|x coordinate of the curve at parameter t.}}
 
{{param|number|x|x coordinate of the curve at parameter t.}}
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love.graphics.circle("fill", x, y, 8)
 
love.graphics.circle("fill", x, y, 8)
 
love.graphics.line(curve:render())
 
love.graphics.line(curve:render())
end
 
</source>
 
 
=== Evaluate a point from any amoount of control points ===
 
 
<source lang="lua">
 
local function evaluate (curve, t)
 
local ccpc = curve:getControlPointCount( )
 
if ccpc > 1 then
 
return curve:evaluate(t)
 
elseif ccpc == 1 then
 
return curve:getControlPoint(1)
 
else
 
return 0, 0
 
end
 
 
end
 
end
 
</source>
 
</source>

Latest revision as of 17:07, 14 August 2022

Available since LÖVE 0.9.0
This function is not supported in earlier versions.

Evaluate Bézier curve at parameter t. The parameter must be between 0 and 1 (inclusive) and there must be at least two control points for the curve.

This function can be used to move objects along paths or tween parameters. However it should not be used to render the curve - see BezierCurve:render for that purpose.

Function

Synopsis

x, y = BezierCurve:evaluate( t )

Arguments

number t
Where to evaluate the curve. Must be between 0 and 1.

Returns

number x
x coordinate of the curve at parameter t.
number y
y coordinate of the curve at parameter t.

Examples

Make a circle follow a curve

local controlPoints = {125,125, 125,225, 175,125, 225,125}
local curve         = love.math.newBezierCurve(controlPoints)

function love.draw()
	local time     = love.timer.getTime()
	local loopTime = 4
	local t        = (time / loopTime) % 1
	local x, y     = curve:evaluate(t)

	love.graphics.circle("fill", x, y, 8)
	love.graphics.line(curve:render())
end

See Also


Other Languages