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help with 3D Line actor



  • hiya, am struggling to understand how to correctly position a line using the 3D Line actor inputs and was wondering if there's anywhere i could find an explanation or some help?

    cheers, Mr J


  • Beta Platinum

    @mr_j

    A line is drawn between two points in 3D space. So x1,y1,z1 is one point and x2,y2,z2 Is the second point. If I remember correctly the 0 point is in the centre of the 3D space and the range is -100/100 in the x and y.

    Kind Regards

    Russell



  • thanks for your reply @bonemap 

    so if the actor inputs x, y and z translate are a translation along the x, y and z axis from -100 to +100... how do these relate to a line drawn between two points in the 3D space?

    i've drawn and line between two x1,y1 and x2,y2 points and depending on the z translate value it's visible, partially visible or not visible... am assuming translate has something to do with the viewing angle

    and how does this all relate to how the output is treated on the stage? translating x, y and z from -100 to +100 implies the stage is square but if it isn't (i.e. output is 1920 x 1080) how is the output scaled?

    BTW: thanks for your recent reply back to the drawing sound responsive waveforms post, i've been playing with this further and am loving some of the results... will hopefully be able to expand further once i've figured out more about the 3D Line actor

    From one antipodean to another, Mr J 


  • Beta Platinum

    @mr_j said:

    100 to +100 implies the stage is square but if it isn't (i.e. output is 1920 x 1080) how is the output scaled?

     Hi,

    One thing that is confusing about the 3D Line actor is that the line weight itself (its thickness) does not change as expected when moving along the z axis. Normally you would expect a 3D object to gain in perceived size as it is moved closer to the viewport/camera. But that is not the case with this particular 3D module. Therefore, to create the illusion of the line being closer or further away you only have the Line Size property available. I don't know why it is the case — that is a question for @mark. I think it is to keep the line crisp and without  visual aliasing as it moves on different angles, although it would be good to have the ability to turn on auto scaling if it was an option.

    Thinking in terms of scale is not quite right for the Z axis in 3D space. It helps to use the 3D Stage Orientation actor, because it represents the 'camera' or view port that is presented on the Stage and has a FOV (Field of View property). In Isadora 3D space the ratio of the video frame does not effect the calibration of 3D elements being configured. (if you were working with the Lines actor or Shapes which are 2d then the frame ratio will have an impact). It helps to think of the 3D space as a field of view of a viewport/camera frame looking at world coordinates in front of it. In fact the viewport is within the coordinates and can be moved in 3D space as well using the properties of the 3D Stage Orientation.

    Best Wishes

    Russell