Revision Difference
cam.Start3D2D#524920
<function name="Start3D2D" parent="cam" type="libraryfunc">
	<description>
Sets up a new 2D rendering context. Must be finished by <page>cam.End3D2D</page>. This function pushes a new matrix onto the stack. (<page>cam.PushModelMatrix</page>)
⤶
Matrix formula:⤶
```⤶
local m = Matrix()⤶
m:SetAngles(angles)⤶
m:SetTranslation(pos)⤶
m:SetScale(Vector(scale, -scale, 1))⤶
```⤶
<rendercontext hook="false" type="2D"></rendercontext>
<rendercontext hook="false" type="3D"></rendercontext>
<warning>This should be closed by <page>cam.End3D2D</page> otherwise the game crashes</warning>
	</description>
	<realm>Client</realm>
	<args>
		<arg name="pos" type="Vector">Origin of the 3D2D context, ie. the top left corner, (0, 0).</arg>
		<arg name="angles" type="Angle">Angles of the 3D2D context.
+x in the 2d context corresponds to +x of the angle (its forward direction).
+y in the 2d context corresponds to -y of the angle (its right direction).
If (dx, dy) are your desired (+x, +y) unit vectors, the angle you want is dx:AngleEx(dx:Cross(-dy)).</arg>
		<arg name="scale" type="number">The scale of the render context.
If scale is 1 then 1 pixel in 2D context will equal to 1 unit in 3D context.</arg>
	</args>
</function>
<example>
<description>Makes a floating rectangle with text above where the player is looking at, pointing at the player</description>
<code>
hook.Add("PostDrawOpaqueRenderables", "example", function()
	-- Get the game's camera angles
	local angle = EyeAngles()
	-- Only use the Yaw component of the angle
	angle = Angle( 0, angle.y, 0 )
	-- Apply some animation to the angle
	angle.y = angle.y + math.sin( CurTime() ) * 10
	-- Correct the angle so it points at the camera
	-- This is usually done by trial and error using Up(), Right() and Forward() axes
	angle:RotateAroundAxis( angle:Up(), -90 )
	angle:RotateAroundAxis( angle:Forward(), 90 )
	-- A trace just for a position
	local trace = LocalPlayer():GetEyeTrace()
	local pos = trace.HitPos
	-- Raise the hitpos off the ground by 20 units and apply some animation
	pos = pos + Vector( 0, 0, math.cos( CurTime() / 2 ) + 20 )
	-- Notice the scale is small, so text looks crispier
	cam.Start3D2D( pos, angle, 0.1 )
		-- Get the size of the text we are about to draw
		local text = "Testing"
		surface.SetFont( "Default" )
		local tW, tH = surface.GetTextSize( "Testing" )
		-- This defines amount of padding for the box around the text
		local pad = 5
		-- Draw a rectable. This has to be done before drawing the text, to prevent overlapping
		-- Notice how we start drawing in negative coordinates
		-- This is to make sure the 3d2d display rotates around our position by its center, not left corner
		surface.SetDrawColor( 0, 0, 0, 255 )
		surface.DrawRect( -tW / 2 - pad, -pad, tW + pad * 2, tH + pad * 2 )
		-- Draw some text
		draw.SimpleText( "Testing", "Default", -tW / 2, 0, color_white )
	cam.End3D2D()
end )
</code>
</example>
<example>
	<code>
hook.Add("PostDrawOpaqueRenderables", "example", function()
	local trace = LocalPlayer():GetEyeTrace()
	local angle = trace.HitNormal:Angle()
		
	render.DrawLine( trace.HitPos, trace.HitPos + 8 * angle:Forward(), Color( 255, 0, 0 ), true )
	render.DrawLine( trace.HitPos, trace.HitPos + 8 * -angle:Right(), Color( 0, 255, 0 ), true )
	render.DrawLine( trace.HitPos, trace.HitPos + 8 * angle:Up(), Color( 0, 0, 255 ), true )
		
	cam.Start3D2D( trace.HitPos, angle, 1 )
		surface.SetDrawColor( 255, 165, 0, 255 )
		surface.DrawRect( 0, 0, 8, 8 )
		render.DrawLine( Vector( 0, 0, 0 ), Vector( 8, 8, 8 ), Color( 100, 149, 237, 255 ), true )
	cam.End3D2D()
end )
	</code>
	<output><image src="cam.Start3D2D_example_1.png"/></output>
</example>
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