math.BSplinePoint

Vector math.BSplinePoint( number fraction, table points, number fractionMax )

Description

Basic code for Bézier-Spline algorithm.

Arguments

1 number fraction

A number in the range [0,fractionMax] which controls which location along the spline's length should be evaluated as the return value.

2 table points

A table of Vectors that form the spline.

There must be at least 4 points.

3 number fractionMax

The maximum value of the fraction argument.

The most common value for this is 1.

Returns

1 Vector

The point on the Bézier curve that corresponds to the given fraction argument.

Example

Makes a black box that moves a Bézier curve made out of 4 points.

local points = { Vector( 100, 100, 0 ), Vector( 200, 200, 0 ), Vector( 300, 100, 0 ), Vector( 400, 200, 0 ) } hook.Add( "HUDPaint", "BSplinePointExample", function() -- Draw the points for _, p in ipairs( points ) do draw.RoundedBox( 0, p.x - 2, p.y - 2, 4, 4, color_white ) end -- Draw the spline surface.SetDrawColor( 255, 0, 0, 255 ) local lastPos = math.BSplinePoint( 0, points, 1 ) for i=0, 10 do local pos = math.BSplinePoint( i / 10, points, 1 ) surface.DrawLine( lastPos.x, lastPos.y, pos.x, pos.y ) lastPos = pos end -- Draw a point on the spline local pos = math.BSplinePoint( ( math.cos( CurTime() ) + 1 ) / 2, points, 1 ) draw.RoundedBox( 0, pos.x - 2, pos.y - 2, 4, 4, color_black ) end )

Example

Interactive demo

local PANEL = {} PANEL.Init = function( panel ) panel:SetText( "" ) panel:SetSize( 24, 24 ) panel.Dragging = false end PANEL.OnCursorMoved = function( panel, x, y ) if ( panel.Dragging ) then local x, y = input.GetCursorPos() panel:SetPos( panel.StartPos.x + x - panel.CursorPos.x , panel.StartPos.y + y - panel.CursorPos.y ) end end PANEL.OnMousePressed = function( panel, x, y ) panel.Dragging = true local x, y = input.GetCursorPos() panel.CursorPos = { x = x, y = y } local x, y = panel:GetPos() panel.StartPos = { x = x, y = y } end PANEL.OnMouseReleased = function( panel, x, y ) panel.Dragging = false end PANEL.OnCursorExited = PANEL.OnCursorMoved local MovableButton = vgui.RegisterTable( PANEL, "DButton" ) local f = vgui.Create( "DFrame" ) f:SetSize( 500, 500 ) f:Center() f:MakePopup() local oldPaint = f.Paint f.Paint = function( pnl, w, h ) oldPaint( pnl, w, h ) local points = {} for k, pnl in ipairs( pnl:GetChildren() ) do local x, y = pnl:GetPos() if ( pnl.Dragging != nil ) then table.insert( points, Vector( x, y, 0 ) ) pnl:SetText( #points ) end end surface.SetDrawColor( 255, 0, 0, 255 ) local lastPos = math.BSplinePoint( 0, points, 1 ) for i=0, 32 do local pos = math.BSplinePoint( i / 32, points, 1 ) surface.DrawLine( lastPos.x, lastPos.y, pos.x, pos.y ) lastPos = pos end end vgui.CreateFromTable( MovableButton, f ):SetPos( 100, 100 ) vgui.CreateFromTable( MovableButton, f ):SetPos( 200, 200 ) vgui.CreateFromTable( MovableButton, f ):SetPos( 300, 100 ) vgui.CreateFromTable( MovableButton, f ):SetPos( 400, 200 ) local addBtn = vgui.Create( "DButton", f ) addBtn:Dock( TOP ) addBtn:SetText( "Add point" ) addBtn.DoClick = function() vgui.CreateFromTable( MovableButton, f ):SetPos( VectorRand( 20, 450 ):Unpack() ) end