DxDrawPrimitive

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Revision as of 17:15, 23 January 2023 by Dragon (talk | contribs) (added another example using the linestrip type primitive)
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This function draws a 2D primitive shape across the screen - rendered for one frame. This should be used in conjunction with onClientRender in order to display continuously.

Syntax

bool dxDrawPrimitive ( string pType, bool postGUI, table vertice1 [, table vertice2, ...] )

Required Arguments

  • pType: Type of primitive to be drawn.
  • postGUI: A bool representing whether the line should be drawn on top of or behind any ingame GUI (rendered by CEGUI).
  • vertices: Tables representing each primitive vertice, required amount of them is determined by primitive type.

Allowed types

Available primitive types.

More info on primitives may be found on this MSDN site

  • pointlist: Renders the vertices as a collection of isolated points.
  • linelist: Renders the vertices as a list of isolated straight line segments.
  • linestrip: Renders the vertices as a single polyline.
  • trianglelist: Renders the specified vertices as a sequence of isolated triangles. Each group of three vertices defines a separate triangle.
  • trianglestrip: Renders the vertices as a triangle strip.
  • trianglefan: Renders the vertices as a triangle fan.

Vertices format

  • posX: An float representing the absolute X position of the vertice, represented by pixels on the screen.
  • posY: An float representing the absolute Y position of the vertice, represented by pixels on the screen.
  • color (optional): An integer of the hex color, produced using tocolor or 0xAARRGGBB (AA = alpha, RR = red, GG = green, BB = blue). If it's not specified, white color is used.

Returns

Returns a true if the operation was successful, false otherwise.

Example

Click to collapse [-]
Example 1

This is a small example that creates trianglefan primitive with vertices in places that user clicks. It assigns every vertice random color. 

local vertices = {}
function onClick(btn, state, x, y)
	if btn ~= "left" then return end
	if state ~= "up" then return end
	local vertice = {x, y, tocolor(math.random(255), math.random(255), math.random(255))}
	table.insert(vertices, vertice)
end
addEventHandler("onClientClick", root, onClick)

function draw()
	dxDrawPrimitive("trianglefan", true, unpack(vertices))
end
addEventHandler("onClientPreRender", root, draw)
Click to collapse [-]
Example 2

This example draws one complete oscillation of a sine wave starting in the center of the players screen using a linestrip type primitive. 

local screenSizeX,screenSizeY = guiGetScreenSize() -- save the current screen dimensions
local sinCoords = {}

function resStart() -- do all this once during "onClientResourceStart", rather than every frame
	local range = math.pi * 2 -- to get 1 complete oscillation of the sine wave we need the range from 0 to 2pi
	local resolution = 100 -- resolution in this example means in how many steps we draw the linestrip, higher resolution means smoother curve at the expense of longer computation time
	local scale = 50
	for i=0,range,range/resolution do -- "loop through this [resolution] times, starting at 0 and ending at [range]"
		local x = screenSizeX * 0.5 + i * scale -- start at the center of the screen and go from there
		local y = screenSizeY * 0.5 - math.sin(i) * scale -- subtract rather than add because greater y value means lower on the screen, which is the opposite of what we're used to seeing in graphs
		table.insert(sinCoords,{x,y})
	end
end
addEventHandler("onClientResourceStart",getResourceRootElement(getThisResource()), resStart)

function exampleRender()
	dxDrawPrimitive("linestrip",true,unpack(sinCoords)) -- render a linestrip type primitive with the coordinates we calculated earlier to draw our sine wave
end
addEventHandler("onClientRender",getRootElement(),exampleRender)

See Also

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