fire arrow at given angle

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• hgvyas123 Guru

  September 2013

  this is the what i have done but it is not working any idea or other solution

  local myRot = self.mySphere:getRotation() self.mySphere:setRotation(0)----to easily create the physics body local body = world:createBody{type = b2.DYNAMIC_BODY, position = {x = self.mySphere:getX(), y = self.mySphere:getY()}}   body.name = name   local shape = b2.PolygonShape.new() shape:setAsBox(self.mySphere:getWidth()*0.5, self.mySphere:getHeight()*0.5) body:createFixture{shape = shape, density = 1, restitution = 0.2, friction = 0.3} self.mySphere.body = body   self.mySphere.body:setAngle(myRot*math.pi/180)--to reset the angle of sphere   --find 4 points to throw the sphere local point1X = self.mySphere:getX()+self.mySphere:getWidth()*math.cos(myRot*math.pi/180) local point1Y = self.mySphere:getY()+self.mySphere:getHeight()*math.sin(myRot*math.pi/180) local point2X = self.mySphere:getX()-self.mySphere:getWidth()*math.cos(myRot*math.pi/180) local point2Y = self.mySphere:getY()-self.mySphere:getHeight()*math.sin(myRot*math.pi/180)   local strength = 0.1   local xVect = (point1X-point2X)*strength local yVect = (point1Y-point2Y)*strength     self.mySphere.body:applyLinearImpulse(xVect, yVect, self.mySphere:getX(),self.mySphere:getY())

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• ar2rsawseen Maintainer

  September 2013 edited September 2013 Accepted Answer

  If you have angle, you only need to calculate the vectors based on the angle:

  local xVect = -math.sin(self.mySphere.body:getAngle())*strength local yVect = math.cos(self.mySphere.body:getAngle())*strength self.mySphere.body:applyLinearImpulse(xVect, yVect, self.mySphere:getX(),self.mySphere:getY())

  depending on your original image, how it is rotated, you may need to apply offset angle, like your arrows image is pointing to the right, rotate it for 90 degrees by applying -math.pi/2 to make the default direction up

  local xVect = -math.sin(self.mySphere.body:getAngle()-math.pi/2)*strength local yVect = math.cos(self.mySphere.body:getAngle()-math.pi/2)*strength self.mySphere.body:applyLinearImpulse(xVect, yVect, self.mySphere:getX(),self.mySphere:getY())

  http://appcodingeasy.com/Gideros-Mobile

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• hgvyas123 Guru

  September 2013

  yeah it worked i was fighting with some points since almost two hours
  
  

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