GetElementMatrix: Difference between revisions

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(Added OOP syntax, fixed tabs in examples and some minor changes)
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{{Client function}}
{{Client function}}
__NOTOC__  
__NOTOC__  
This function gets an element's transform matrix. This contains 16 float values that multiplied to a point will give you the point transformed. It is most useful for matrix calculations such as calculating offsets. For further information, please refer to a tutorial of matrices in computer graphics programming.
This function gets an [[element]]'s transform [[matrix]]. This contains 16 float values that multiplied to a point will give you the point transformed. It is most useful for matrix calculations such as calculating offsets. For further information, please refer to a tutorial of matrices in computer graphics programming.
{{Note|The matrix returned by this function is [http://bugs.mtasa.com/view.php?id{{=}}6984 not setup correctly for some calculations.] unless the '''legacy''' argument is set to '''false'''}}
{{Note|The [[matrix]] returned by this function is [http://bugs.mtasa.com/view.php?id{{=}}6984 not setup correctly for some calculations] unless the '''legacy''' argument is set to '''''false'''''.}}
{{Tip|''For matrix manipulation which goes beyond the basic examples given on this page, see the [[Lua matrix library]].''}}
{{Tip|''For [[matrix]] manipulation which goes beyond the basic examples given on this page, see the [[Lua matrix library]].'' If you are using MTA: SA 1.4 or higher, using the built-in [[matrix]] class is also recommended.}}
==Syntax==
==Syntax==
<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
table getElementMatrix ( element theElement [, bool legacy = true ] )      
table getElementMatrix ( element theElement [, bool legacy = true ] )
</syntaxhighlight>  
</syntaxhighlight>
{{OOP||[[element]]:getMatrix|matrix}}


===Required Arguments===  
===Required Arguments===  
*'''theElement:''' The element which you wish to retrieve the matrix for
*'''theElement:''' The [[element]] which you wish to retrieve the [[matrix]] for.


===Optional Arguments===  
===Optional Arguments===  
*'''legacy :''' Set to false to return correctly setup matrix. (i.e. Last column in the first 3 rows set to zero.)
*'''legacy:''' Set to ''false'' to return correctly setup [[matrix]] (i.e. Last column in the first 3 rows set to zero).


===Returns===
===Returns===
Returns a multi-dimensional array containing a 4x4 matrix. Returns false if the element is not streamed in, and not a vehicle or ped.
Returns a multi-dimensional array (which can be transformed into a proper [[matrix]] class using ''Matrix.create'' method) containing a 4x4 matrix. Returns ''false'' if the element is not streamed in, and not a [[vehicle]], [[ped]] or [[object]].


==Example==  
==Example==  
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<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
function getPositionFromElementOffset(element,offX,offY,offZ)
function getPositionFromElementOffset(element,offX,offY,offZ)
local m = getElementMatrix ( element )  -- Get the matrix
    local m = getElementMatrix ( element )  -- Get the matrix
local x = offX * m[1][1] + offY * m[2][1] + offZ * m[3][1] + m[4][1]  -- Apply transform
    local x = offX * m[1][1] + offY * m[2][1] + offZ * m[3][1] + m[4][1]  -- Apply transform
local y = offX * m[1][2] + offY * m[2][2] + offZ * m[3][2] + m[4][2]
    local y = offX * m[1][2] + offY * m[2][2] + offZ * m[3][2] + m[4][2]
local z = offX * m[1][3] + offY * m[2][3] + offZ * m[3][3] + m[4][3]
    local z = offX * m[1][3] + offY * m[2][3] + offZ * m[3][3] + m[4][3]
return x, y, z                              -- Return the transformed point
    return x, y, z                              -- Return the transformed point
end
end


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<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
function getMatrixLeft(m)
function getMatrixLeft(m)
        return m[1][1], m[1][2], m[1][3]
    return m[1][1], m[1][2], m[1][3]
end
end
function getMatrixForward(m)
function getMatrixForward(m)
        return m[2][1], m[2][2], m[2][3]
    return m[2][1], m[2][2], m[2][3]
end
end
function getMatrixUp(m)
function getMatrixUp(m)
        return m[3][1], m[3][2], m[3][3]
    return m[3][1], m[3][2], m[3][3]
end
end
function getMatrixPosition(m)
function getMatrixPosition(m)
        return m[4][1], m[4][2], m[4][3]
    return m[4][1], m[4][2], m[4][3]
end
end


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</syntaxhighlight>
</syntaxhighlight>


This example function shows you what getElementMatrix does internally  
This example function shows you what getElementMatrix does internally.
<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
function getElementMatrix(element)
function getElementMatrix(element)
local rx, ry, rz = getElementRotation(element, "ZXY")
    local rx, ry, rz = getElementRotation(element, "ZXY")
rx, ry, rz = math.rad(rx), math.rad(ry), math.rad(rz)
    rx, ry, rz = math.rad(rx), math.rad(ry), math.rad(rz)
local matrix = {}
    local matrix = {}
matrix[1] = {}
    matrix[1] = {}
matrix[1][1] = math.cos(rz)*math.cos(ry) - math.sin(rz)*math.sin(rx)*math.sin(ry)
    matrix[1][1] = math.cos(rz)*math.cos(ry) - math.sin(rz)*math.sin(rx)*math.sin(ry)
matrix[1][2] = math.cos(ry)*math.sin(rz) + math.cos(rz)*math.sin(rx)*math.sin(ry)
    matrix[1][2] = math.cos(ry)*math.sin(rz) + math.cos(rz)*math.sin(rx)*math.sin(ry)
matrix[1][3] = -math.cos(rx)*math.sin(ry)
    matrix[1][3] = -math.cos(rx)*math.sin(ry)
matrix[1][4] = 1
    matrix[1][4] = 1
   
matrix[2] = {}
    matrix[2] = {}
matrix[2][1] = -math.cos(rx)*math.sin(rz)
    matrix[2][1] = -math.cos(rx)*math.sin(rz)
matrix[2][2] = math.cos(rz)*math.cos(rx)
    matrix[2][2] = math.cos(rz)*math.cos(rx)
matrix[2][3] = math.sin(rx)
    matrix[2][3] = math.sin(rx)
matrix[2][4] = 1
    matrix[2][4] = 1
matrix[3] = {}
    matrix[3] = {}
matrix[3][1] = math.cos(rz)*math.sin(ry) + math.cos(ry)*math.sin(rz)*math.sin(rx)
    matrix[3][1] = math.cos(rz)*math.sin(ry) + math.cos(ry)*math.sin(rz)*math.sin(rx)
matrix[3][2] = math.sin(rz)*math.sin(ry) - math.cos(rz)*math.cos(ry)*math.sin(rx)
    matrix[3][2] = math.sin(rz)*math.sin(ry) - math.cos(rz)*math.cos(ry)*math.sin(rx)
matrix[3][3] = math.cos(rx)*math.cos(ry)
    matrix[3][3] = math.cos(rx)*math.cos(ry)
matrix[3][4] = 1
    matrix[3][4] = 1
matrix[4] = {}
    matrix[4] = {}
matrix[4][1], matrix[4][2], matrix[4][3] = getElementPosition(element)
    matrix[4][1], matrix[4][2], matrix[4][3] = getElementPosition(element)
matrix[4][4] = 1
    matrix[4][4] = 1
return matrix
    return matrix
end
end
</syntaxhighlight>
</syntaxhighlight>

Revision as of 16:32, 26 November 2014

This function gets an element's transform matrix. This contains 16 float values that multiplied to a point will give you the point transformed. It is most useful for matrix calculations such as calculating offsets. For further information, please refer to a tutorial of matrices in computer graphics programming.

[[{{{image}}}|link=|]] Note: The matrix returned by this function is not setup correctly for some calculations unless the legacy argument is set to false.
[[{{{image}}}|link=|]] Tip: For matrix manipulation which goes beyond the basic examples given on this page, see the Lua matrix library. If you are using MTA: SA 1.4 or higher, using the built-in matrix class is also recommended.

Syntax

table getElementMatrix ( element theElement [, bool legacy = true ] )

OOP Syntax Help! I don't understand this!

Method: element:getMatrix(...)
Variable: .matrix


Required Arguments

  • theElement: The element which you wish to retrieve the matrix for.

Optional Arguments

  • legacy: Set to false to return correctly setup matrix (i.e. Last column in the first 3 rows set to zero).

Returns

Returns a multi-dimensional array (which can be transformed into a proper matrix class using Matrix.create method) containing a 4x4 matrix. Returns false if the element is not streamed in, and not a vehicle, ped or object.

Example

This example creates a utility function that turns an offset into a position that is relative to the specified element.

function getPositionFromElementOffset(element,offX,offY,offZ)
    local m = getElementMatrix ( element )  -- Get the matrix
    local x = offX * m[1][1] + offY * m[2][1] + offZ * m[3][1] + m[4][1]  -- Apply transform
    local y = offX * m[1][2] + offY * m[2][2] + offZ * m[3][2] + m[4][2]
    local z = offX * m[1][3] + offY * m[2][3] + offZ * m[3][3] + m[4][3]
    return x, y, z                               -- Return the transformed point
end

-- Get the position of a point 3 units to the left of the element:
x,y,z = getPositionFromElementOffset(element,3,0,0)

-- Get the position of a point 2 units in front of the element:
x,y,z = getPositionFromElementOffset(element,0,2,0)

-- Get the position of a point 1 unit above the element:
x,y,z = getPositionFromElementOffset(element,0,0,1)

This example creates some more matrix utility functions

function getMatrixLeft(m)
    return m[1][1], m[1][2], m[1][3]
end
function getMatrixForward(m)
    return m[2][1], m[2][2], m[2][3]
end
function getMatrixUp(m)
    return m[3][1], m[3][2], m[3][3]
end
function getMatrixPosition(m)
    return m[4][1], m[4][2], m[4][3]
end

local mat = getElementMatrix(element)  -- Get the matrix
x,y,z = getMatrixLeft(mat)     -- Get the matrix left direction
x,y,z = getMatrixForward(mat)  -- Get the matrix forward direction
x,y,z = getMatrixUp(mat)       -- Get the matrix up direction

This example function shows you what getElementMatrix does internally.

function getElementMatrix(element)
    local rx, ry, rz = getElementRotation(element, "ZXY")
    rx, ry, rz = math.rad(rx), math.rad(ry), math.rad(rz)
    local matrix = {}
    matrix[1] = {}
    matrix[1][1] = math.cos(rz)*math.cos(ry) - math.sin(rz)*math.sin(rx)*math.sin(ry)
    matrix[1][2] = math.cos(ry)*math.sin(rz) + math.cos(rz)*math.sin(rx)*math.sin(ry)
    matrix[1][3] = -math.cos(rx)*math.sin(ry)
    matrix[1][4] = 1
    
    matrix[2] = {}
    matrix[2][1] = -math.cos(rx)*math.sin(rz)
    matrix[2][2] = math.cos(rz)*math.cos(rx)
    matrix[2][3] = math.sin(rx)
    matrix[2][4] = 1
	
    matrix[3] = {}
    matrix[3][1] = math.cos(rz)*math.sin(ry) + math.cos(ry)*math.sin(rz)*math.sin(rx)
    matrix[3][2] = math.sin(rz)*math.sin(ry) - math.cos(rz)*math.cos(ry)*math.sin(rx)
    matrix[3][3] = math.cos(rx)*math.cos(ry)
    matrix[3][4] = 1
	
    matrix[4] = {}
    matrix[4][1], matrix[4][2], matrix[4][3] = getElementPosition(element)
    matrix[4][4] = 1
	
    return matrix
end

Changelog

Version Description
1.3.0-9.04186 Added legacy argument

See Also