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Function / coding

  1. Jul 26, 2012 #1
    help needed please.. dont need the code. but i need formula or any source that can help me. i want to try code it myself. =)

    can anyone help me with this function:


    // Function to be used to update the position. Given the current position,
    // the direction in which the tank is looking, and the speed it is moving,
    // modify position to the new position
    function UpdatePosition_Axis(ref position, direction, speed)
    {
    *what is this asking for?*
    }

    // Function used to transform a point by an angle and scale, and translated by a position.
    // Follows Linear Transformations: x' = p + A * x
    function TransformPoint(model, position, direction, scale)
    {
    *and this*
    }

    // Function used to render a generic rectangle. It uses the position, angle, and scale to transform
    // each point of the normalized rectangle model, and display the rectangle on the screen
    function RenderRectangle(position, direction, scale, c)
    {
    *sorry, plus this*
    }

    Given: for part b
    // Normalized Model of a rectangle.
    point2d model_top_left = [-0.5, 0.5];
    point2d model_top_right = [ 0.5, 0.5];
    point2d model_bottom_right = [ 0.5, -0.5];
    point2d model_bottom_left = [-0.5, -0.5];


    help is much appreciated. thanks
     
    Last edited: Jul 26, 2012
  2. jcsd
  3. Jul 26, 2012 #2
    What have you tried? What language is this?

    In the first function, you are going to have something like:

    tank.ref_pos = ref_pos;
    tank.speed =speed;
    tank.direction = direction;
     
  4. Jul 26, 2012 #3
    yeah.. i had tried it.. is in HLPL

    my function

    pos.x = pos.x * cos(direction) + speed;
    pos.y = pos.y * sin(direction) + speed;

    but the problem is, the object able to move in x direction but when moving in y direction, the object so off elsewhere.
     
  5. Jul 26, 2012 #4
    Sorry; I don't know HLPL
     
  6. Jul 26, 2012 #5
    thanks for the offer of helping though. =)
     
  7. Jul 27, 2012 #6

    jhae2.718

    User Avatar
    Gold Member

    I just skimmed through the instructions, but to me it seems like you need to do the following:

    1. 2d kinematics, namely [itex]\mathbf{r}(t) = \mathbf{r}_0 + \dot{\mathbf{r}}t[/itex]
    2. Rotation matrix to transfer angle and then add pose vector. (Look at the Wikipedia article on rotation matrices)
    3. Use the given nonrotated rectangle of sides 1 unit and then use linear transformations to scale, rotate, and translate it.
     
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