Wikitude

Dear,

We are trying to position several AR.positionables using as a basis the C++ plugin “MarkerTrackerPlugin” provided with the SDK.

Inside the “updatePositionables” function in the cpp file, the view, world and projection matrix of a single AR.Positionable, instantiated in the javascript file, can be set:

it->second->setWorldMatrix(identity.get());
it->second->setViewMatrix(modelViewMatrix.get());
it->second->setProjectionMatrix(_projectionMatrix.get());

    createOverlays: function createOverlaysFn() {
        var carModel = new AR.Model(
            "assets/car.wt3", {
                scale: {x: 0.01, y: 0.01, z: 0.01 },
                translate: { x: 0.0, y: 0.0, z: 0.0 },
                rotate: { x: 0, y: 0, z: 0 }
            });

        World.positionable = new AR.Positionable("myPositionable", {
            drawables: { cam: carModel }
        });

        World.positionable_2 = new AR.Positionable("myPositionable_2", {
            drawables: { cam: carModel }
        });
    }

std::unordered_map<std::string, wikitude::sdk_core::impl::PositionableWrapper*>::const_iterator it = positionables_.find("myPositionable");
std::unordered_map<std::string, wikitude::sdk_core::impl::PositionableWrapper*>::const_iterator it_2 = positionables_.find("myPositionable_2");

it->second->setWorldMatrix(identity.get());
it->second->setViewMatrix(modelViewMatrix.get());
it->second->setProjectionMatrix(_projectionMatrix.get());

it_2->second->setWorldMatrix(identity.get());
it_2->second->setViewMatrix(modelViewMatrix_2.get());
it_2->second->setProjectionMatrix(_projectionMatrix.get());

However, we are not able to change the position of the two Positionables independently by changing their ViewMatrix (we use two different but similar ViewMatrix) because we always see one single object (the two are overlapped ¿?) as it seems that the ViewMatrix is shared between the two objects. Are we doing something wrong or missing something?

Our final goal is to use the matrix provided by Aruco to position different objects in different locations related to this unique matrix. Is there a way in which this can be done?

Many thanks in advance

Best rewars,

Javier

Dear Andreas Schacherbauer:

We are glad to hear about it and we would be deligthed to try the new API. I would like to point out that last time I forgot to mention that we are developing for the Epson BT-200.

At the same time, I would want to ask yout if there is any way in which we could get the position of the camera from either the javascript or the c++ plugin. Thank you in advance for enligthening us.

We are looking forward to hearing from you,

Javier Román

Hi Andreas:

Thank you for the reply. We would be glad to try the standard Android SDK.

However, we are still trying to figure out how to get the position of a given recognized  ImageTarget with the JS API. Could you enlighten us on how to get the translation and rotation of the device's camera related to a target once it has been detected?

As far as we know, the ImageTrackable class has the onImageRecognized event where the related ImageTarget is passed as an argument. The ImageTarget has two methods (getRotationTo, getTranslationTo) that return the translation/rotation to other target but as a number instead of a matrix, which is bit annoying. Moreover, the traslation/rotation of the target has to be calculated with regard to other detected target (we want the raw position, the one realted to the camera ). Is there a better way to get the transformation matrix realted to the camera? Are we missing something?

Finally, we have a quick question about the SDU unit used to position drawables. We want to make sure that the conversion between the SDU unit and e.g. milimeters is as easy as multiplying by the height of the target in milimeters.

Many thanks in advance,

Javier