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432 lines
10 KiB
ReStructuredText
432 lines
10 KiB
ReStructuredText
hump.vector-light
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=================
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::
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vector = require "hump.vector-light"
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An table-free version of :doc:`hump.vector <vector>`. Instead of a vector type,
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``hump.vector-light`` provides functions that operate on numbers.
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.. note::
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Using this module instead of :doc:`hump.vector <vector>` may result in
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faster code, but does so at the expense of speed of development and code
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readability. Unless you are absolutely sure that your code is
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significantly slowed down by :doc:`hump.vector <vector>`, I recommend using
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it instead.
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**Example**::
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function player:update(dt)
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local dx,dy = 0,0
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if love.keyboard.isDown('left') then
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dx = -1
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elseif love.keyboard.isDown('right') then
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dx = 1
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end
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if love.keyboard.isDown('up') then
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dy = -1
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elseif love.keyboard.isDown('down') then
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dy = 1
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end
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dx,dy = vector.normalize(dx, dy)
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player.velx, player.vely = vector.add(player.velx, player.vely,
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vector.mul(dy, dx, dy))
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if vector.len(player.velx, player.vely) > player.max_velocity then
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player.velx, player.vely = vector.mul(player.max_velocity,
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vector.normalize(player.velx, player.vely)
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end
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player.x = player.x + dt * player.velx
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player.y = player.y + dt * player.vely
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end
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Function Reference
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------------------
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.. function:: vector.str(x,y)
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:param numbers x,y: The vector.
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:returns: The string representation.
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Produce a human-readable string of the form ``(x,y)``.
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Useful for debugging.
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**Example**::
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print(vector.str(love.mouse.getPosition()))
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.. function:: vector.fromPolar(angle, radius)
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:param number angle: Angle of the vector in radians.
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:param number radius: Length of the vector.
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:returns: ``x``, ``y``: The vector in cartesian coordinates.
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Convert polar coordinates to cartesian coordinates.
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The ``angle`` is measured against the vector (1,0), i.e., the x axis.
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**Examples**::
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x,y = vector.polar(math.pi,10)
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.. function:: vector.toPolar(x, y)
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:param numbers x,y: A vector.
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:returns: ``angle``, ``radius``: The vector in polar coordinates.
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Convert the vector to polar coordinates, i.e., the angle and the radius/lenth.
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**Example**::
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-- complex multiplication
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phase1, abs1 = vector.toPolar(re1, im1)
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phase2, abs2 = vector.toPolar(re2, im2)
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vector.fromPolar(phase1+phase2, abs1*abs2)
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.. function:: vector.mul(s, x,y)
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:param number s: A scalar.
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:param numbers x,y: A vector.
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:returns: ``x*s, y*s``.
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Computes ``x*s,y*s``. The order of arguments is chosen so that it's possible to
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chain operations (see example).
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**Example**::
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velx,vely = vec.mul(dt, vec.add(velx,vely, accx,accy))
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.. function:: vector.div(s, x,y)
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:param number s: A scalar.
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:param numbers x,y: A vector.
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:returns: ``x/s, y/s``.
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Computes ``x/s,y/s``. The order of arguments is chosen so that it's possible to
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chain operations (see example).
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**Example**::
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x,y = vec.div(self.zoom, x-w/2, y-h/2)
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.. function:: vector.add(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1+x2, x1+x2``.
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Computes the sum \\((x1+x2, y1+y2)\\)`` of two vectors. Meant to be used in
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conjunction with other functions like :func:`vector.mul`.
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**Example**::
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player.x,player.y = vector.add(player.x,player.y, vector.mul(dt, dx,dy))
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.. function:: vector.sub(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1-x2, x1-x2``.
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Computes the difference \\((x1-x2, y1-y2)\\) of two vectors. Meant to be used in
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conjunction with other functions like :func:`vector.mul`.
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**Example**::
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dx,dy = vector.sub(400,300, love.mouse.getPosition())
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.. function:: vector.permul(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1*x2, y1*y2``.
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Component-wise multiplication, i.e.: ``x1*x2, y1*y2``.
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**Example**::
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x,y = vector.permul(x,y, 1,1.5)
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.. function:: vector.dot(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1*x2 + y1*y2``.
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Computes the `dot product <http://en.wikipedia.org/wiki/Dot_product>`_ of two
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vectors: ``x1*x2 + y1*y2``.
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**Example**::
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cosphi = vector.dot(rx,ry, vx,vy)
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.. function:: vector.cross(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1*y2 - y1*x2``.
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Computes the `cross product <http://en.wikipedia.org/wiki/Cross_product>`_ of
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two vectors: ``x1*y2 - y1*x2``.
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**Example**::
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parallelogram_area = vector.cross(ax,ay, bx,by)
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.. function:: vector.vector.det(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1*y2 - y1*x2``.
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Alias to :func:`vector.cross`.
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**Example**::
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parallelogram_area = vector.det(ax,ay, bx,by)
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.. function:: vector.eq(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1 == x2 and y1 == y2``
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Test for equality.
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**Example**::
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if vector.eq(x1,y1, x2,y2) then be.happy() end
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.. function:: vector.le(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1 <= x2 and y1 <= y2``.
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Test for partial lexicographical order, ``<=``.
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**Example**::
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if vector.le(x1,y1, x2,y2) then be.happy() end
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.. function:: vector.lt(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: ``x1 < x2 or (x1 == x2) and y1 <= y2``.
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Test for strict lexicographical order, ``<``.
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**Example**::
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if vector.lt(x1,y1, x2,y2) then be.happy() end
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.. function:: vector.len(x,y)
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:param numbers x,y: The vector.
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:returns: Length of the vector.
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Get length of a vector, i.e. ``math.sqrt(x*x + y*y)``.
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**Example**::
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distance = vector.len(love.mouse.getPosition())
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.. function:: vector.len2(x,y)
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:param numbers x,y: The vector.
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:returns: Squared length of the vector.
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Get squared length of a vector, i.e. ``x*x + y*y``.
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**Example**::
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-- get closest vertex to a given vector
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closest, dsq = vertices[1], vector.len2(px-vertices[1].x, py-vertices[1].y)
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for i = 2,#vertices do
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local temp = vector.len2(px-vertices[i].x, py-vertices[i].y)
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if temp < dsq then
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closest, dsq = vertices[i], temp
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end
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end
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.. function:: vector.dist(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: The distance of the points.
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Get distance of two points. The same as ``vector.len(x1-x2, y1-y2)``.
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**Example**::
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-- get closest vertex to a given vector
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-- slightly slower than the example using len2()
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closest, dist = vertices[1], vector.dist(px,py, vertices[1].x,vertices[1].y)
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for i = 2,#vertices do
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local temp = vector.dist(px,py, vertices[i].x,vertices[i].y)
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if temp < dist then
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closest, dist = vertices[i], temp
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end
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end
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.. function:: vector.dist2(x1,y1, x2,y2)
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:param numbers x1,y1: First vector.
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:param numbers x2,y2: Second vector.
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:returns: The squared distance of two points.
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Get squared distance of two points. The same as ``vector.len2(x1-x2, y1-y2)``.
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**Example**::
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-- get closest vertex to a given vector
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closest, dsq = vertices[1], vector.dist2(px,py, vertices[1].x,vertices[1].y)
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for i = 2,#vertices do
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local temp = vector.dist2(px,py, vertices[i].x,vertices[i].y)
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if temp < dsq then
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closest, dsq = vertices[i], temp
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end
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end
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.. function:: vector.normalize(x,y)
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:param numbers x,y: The vector.
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:returns: Vector with same direction as the input vector, but length 1.
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Get normalized vector, i.e. a vector with the same direction as the input
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vector, but with length 1.
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**Example**::
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dx,dy = vector.normalize(vx,vy)
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.. function:: vector.rotate(phi, x,y)
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:param number phi: Rotation angle in radians.
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:param numbers x,y: The vector.
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:returns: The rotated vector
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Get a rotated vector.
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**Example**::
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-- approximate a circle
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circle = {}
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for i = 1,30 do
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local phi = 2 * math.pi * i / 30
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circle[i*2-1], circle[i*2] = vector.rotate(phi, 0,1)
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end
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.. function:: vector.perpendicular(x,y)
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:param numbers x,y: The vector.
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:returns: A vector perpendicular to the input vector
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Quick rotation by 90°. The same (but faster) as ``vector.rotate(math.pi/2, x,y)``.
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**Example**::
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nx,ny = vector.normalize(vector.perpendicular(bx-ax, by-ay))
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.. function:: vector.project(x,y, u,v)
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:param numbers x,y: The vector to project.
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:param numbers u,v: The vector to project onto.
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:returns: The projected vector.
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Project vector onto another vector.
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**Example**::
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vx_p,vy_p = vector.project(vx,vy, ax,ay)
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.. function:: vector.mirror(x,y, u,v)
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:param numbers x,y: The vector to mirror.
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:param numbers u,v: The vector defining the axis.
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:returns: The mirrored vector.
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Mirrors vector on the axis defined by the other vector.
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**Example**::
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vx,vy = vector.mirror(vx,vy, surface.x,surface.y)
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.. function:: vector.angleTo(ox,y, u,v)
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:param numbers x,y: Vector to measure the angle.
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:param numbers u,v (optional): Reference vector.
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:returns: Angle in radians.
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Measures the angle between two vectors. ``u`` and ``v`` default to ``0`` if omitted,
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i.e. the function returns the angle to the coordinate system.
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**Example**::
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lean = vector.angleTo(self.upx, self.upy, 0,1)
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if lean > .1 then self:fallOver() end
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.. function:: vector.trim(max_length, x,y)
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:param number max_length: Maximum allowed length of the vector.
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:param numbers x,y: Vector to trum.
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:returns: The trimmed vector.
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Trim the vector to ``max_length``, i.e. return a vector that points in the same
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direction as the source vector, but has a magnitude smaller or equal to
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``max_length``.
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**Example**::
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vel_x, vel_y = vector.trim(299792458,
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vector.add(vel_x, vel_y,
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vector.mul(mass * dt, force_x, force_y)))
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