Mouse xy to world coordinates with GeRayCollider

  • On 22/02/2017 at 04:41, xxxxxxxx wrote:

    User Information:
    Cinema 4D Version:   R18 
    Platform:   Windows  ;   
    Language(s) :     C++  ;


    I have a tooldata plugin. I need to click on any object, get the normal vector from the polygon I clicked and create in a position based on the direction of the normal.

    Here is what I do:

    1. In ToolData MouseInput, I use ViewportSelect::PickObject to get the clicked object.
    2. Then I use ViewportSelect::Init and ViewportSelect::GetNearestPolygon to get the clicked polygon from that object.
    3. I use polygon_object->CreatePhongNormals() to get the vertex normals, which I use to generate a polygon normal (I average its vertex normals).

    I need to find the clicked position in World space.
    I feel that GeRayCollider's Intersect  is the way to go, but it requires position and direction of the ray.

    Here is how I get screen-to-world position (is it correct ?) :

    Vector cam_pos = base_draw->GetSceneCamera(doc)->GetAbsPos();
    Vector world_pos = base_draw->SW(Vector(mouse_x, mouse_x, cam_pos.z));

    How do I find the direction to the clicked point ?

    Thank you.

  • On 23/02/2017 at 04:54, xxxxxxxx wrote:


    requires a vector with three components: the X and Y coordinate in screen space and the orthogonal distance from that screen space point to the desired world space point.

    ViewportSelect::PickObject() fills a C4DObjectList. For a given object in that list the distance to the hit point can be obtained with C4DObjectList::GetZ(). This distance can be used with BaseView::SW().

    It is not needed to use GeRayCollider.

    best wishes,

  • On 24/02/2017 at 02:08, xxxxxxxx wrote:


    What I need to so is click an object in the viewport and get the 3D point that I clicked (and of course belongs in the surface of the object). I suppose to do that you need to cast a ray from camera position to the clicked point of the object.

    SW is a value related to Camera's position. So, how can I cast a ray from the camera to the clicked point? The intersection with that object will be the 3D point that I need to retrieve.

    Thank you.

  • On 24/02/2017 at 07:02, xxxxxxxx wrote:

    I posted a plugin example with the source code a long time ago called "GeRayCollider_13" that shows how to do this sort of thing:

    Maybe that will be useful to you.


  • On 24/02/2017 at 08:35, xxxxxxxx wrote:


    you can "click" in the viewport using ViewportSelect::PickObject(). The filled C4DObjectList contains the distance needed to use BaseView::SW() to create the desired world space point. It is not needed to cast any rays.

    best wishes,

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