CODEWITHSUNDEEP
javalibgdx
itamarb
itamarb

Reputation: 2599

Hit-testing for decals in Libgdx

I'm using the Decal class (see https://code.google.com/p/libgdx-users/wiki/Decals) for rendering my scene, I need to test if a user has clicked on one of the decals, similar to how it is being implemented for actors in stage.

Is there an implementation for such hit testing? if not, are there any low level API in libgdx that can assist me implementing it?

Upvotes: 1

Views: 914

Answers (1)

GothicFan
GothicFan

Reputation: 86

I have a good method using onTouch() that can be easily changed for the mouse events, 

Decal decal1 = Decal.newDecal(1, 1, textures[1], true);
    decal1.setPosition(1.5f, 0, .5f);
    decals.add(decal1);
    Decal decal2 = Decal.newDecal(1, 1, textures[0], true);
    decal2.setPosition(1f, 0, .5f);
    decals.add(decal2);
    decal2.translate(0, 0, 1f);
//...
for (int i = 0; i < positions.length; i++) {
        positions[i] = new Vector3(decal1.getPosition());
        new Vector3(decal2.getPosition());
    }
    positions[0].set(decal1.getPosition());
    positions[1].set(decal2.getPosition());
    renderer = new ImmediateModeRenderer10();
                Vector3 intersection = new Vector3();


//render method
    Ray pickRay = null;
    renderTowers();
    camera3d.update();
    if (Gdx.input.isTouched()) {
        pickRay = camera3d.getPickRay(Gdx.input.getX(), Gdx.input.getY(),
                TB_X, TB_Y, TB_WIDTH, TB_HEIGHT);
    }
    boolean intersected1 = false;
    boolean intersected2 = false;
    for (int i = 0; i < positions.length; i++) {
        if (pickRay != null
                && Intersector.intersectRaySphere(pickRay, positions[0],
                        .5f, intersection)) {

            gl.glColor4f(1, 0, 0, 1);
            intersected1 = true;

        } else {
            gl.glColor4f(1, 1, 1, 1);
        }
        gl.glPushMatrix();
        gl.glTranslatef(positions[i].x, positions[i].y, positions[i].z);
        gl.glPopMatrix();
    }
    for (int j = 0; j < positions.length; j++) {
        if (pickRay != null
                && Intersector.intersectRaySphere(pickRay, positions[1],
                        .5f, intersection)) {

            gl.glColor4f(1, 0, 0, 1);
            intersected2 = true;

        } else {
            gl.glColor4f(1, 1, 1, 1);
        }
        gl.glPushMatrix();
        gl.glTranslatef(positions[j].x, positions[j].y, positions[j].z);
        gl.glPopMatrix();
    }

    Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(),
            Gdx.graphics.getHeight());
    sbatch.begin();
    if (intersected1) {
        stage.addActor(FireImage);
        camera3d.project(intersection, TB_X, TB_Y, TB_WIDTH, TB_HEIGHT);

    }
    if (intersected2) {
        stage.addActor(IceImage);
        camera3d.project(intersection, TB_X, TB_Y, TB_WIDTH, TB_HEIGHT);

    }

Not very clean but it works for now, parts of this were taken from some excellent online tutorials on ray picking in LIBGDX all credit for that goes to them!!! I just customized it a bit for decals. Hope it helps and if you come up with a cleaner method which I am sure there is one please post, I would love to see it.

Upvotes: 4

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