Bounding box dimentions

[mthor13]

Hi Coppelia and forum,

Is it possible to get the dimension of the bounding box?

I have a legged robot that comprises many parts and I want to use the bounding box width and height in a reinforcement learning algorithm. E.g., I want the robot to walk through narrow corridors and therefore the bounding box width should be as small as possible.

Best Regards,
Mathias Thor

[coppelia]

Hello Mathias,

you can use sim.getObjectFloatParameter together with the appropriate args, e.g.:

Code: Select all

function getObjectBoundingBoxSize(handle)
    local s={}
    local r,m=sim.getObjectFloatParameter(handle,sim.objfloatparam_objbbox_max_x)
    local r,n=sim.getObjectFloatParameter(handle,sim.objfloatparam_objbbox_min_x)
    s[1]=m-n
    local r,m=sim.getObjectFloatParameter(handle,sim.objfloatparam_objbbox_max_y)
    local r,n=sim.getObjectFloatParameter(handle,sim.objfloatparam_objbbox_min_y)
    s[2]=m-n
    local r,m=sim.getObjectFloatParameter(handle,sim.objfloatparam_objbbox_max_z)
    local r,n=sim.getObjectFloatParameter(handle,sim.objfloatparam_objbbox_min_z)
    s[3]=m-n
    return s
end

function getModelBoundingBoxSize(handle)
    local s={}
    local r,m=sim.getObjectFloatParameter(handle,sim.objfloatparam_modelbbox_max_x)
    local r,n=sim.getObjectFloatParameter(handle,sim.objfloatparam_modelbbox_min_x)
    s[1]=m-n
    local r,m=sim.getObjectFloatParameter(handle,sim.objfloatparam_modelbbox_max_y)
    local r,n=sim.getObjectFloatParameter(handle,sim.objfloatparam_modelbbox_min_y )
    s[2]=m-n
    local r,m=sim.getObjectFloatParameter(handle,sim.objfloatparam_modelbbox_max_z)
    local r,n=sim.getObjectFloatParameter(handle,sim.objfloatparam_modelbbox_min_z)
    s[3]=m-n
    return s
end

If you need the bounding box along specific axes for an object or model, or the tight bounding box of a model (the normal model bounding box is the bounding box that encompasses all object bounding boxes inside of the model), then you will have to parse through the vertices of your shapes, using sim.getShapeMesh (and probably some transformation functions). But that will be much slower obviously.

Cheers

[mthor13]

Thanks for the quick response, worked perfectly!