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Enabling Selective Surface-Based Collision

Surface-based collision example

Surface-based collision using collision masks

This example shows how to enable collision detection for a surface using bitmasks. Two boxes (orange and yellow), each with a body and a box shape assigned, and a blue plane are created. We want the yellow box to collide with the surface of the blue plane and the orange box to pass through. So we set the following collision masks for the shapes of the boxes and for the surface of the plane.

Element Mask
Yellow box: shape 0010
Orange box: shape 0001
Plane: surface 0010
Notice
Surface-to-surface collisions cannot be enabled using collision masks.
Source code (UnigineScript)
ObjectMeshStatic box1; 
ObjectMeshStatic box2;
ObjectMeshStatic plane;

/// function, creating a named box of a specified size and color at pos
int create_box(Object &OM, string name, Vec4 color, Vec3 size, Vec3 pos)
{
	// creating an auxiliary mesh with a box surface
	Mesh meshbox = new Mesh();
	meshbox.addBoxSurface("box_surface", size);

	// creating a static mesh object, copying a mesh from the auxiliary one and setting parameters
	OM = new ObjectMeshStatic(meshbox);
	OM.setWorldTransform(translate(pos));
	OM.setMaterial("mesh_base", "*");
	OM.setMaterialParameter("albedo_color", color, 0);	
	OM.setProperty("surface_base", "*");
	OM.setName(name);	

	// assigning a rigid body with our object
	BodyRigid body = class_remove(new BodyRigid(OM));

	// creating a box shape and assigning it to the rigid body of our object	
	ShapeBox shape = class_remove(new ShapeBox(size));
	body.addShape(shape,translate(0.0f, 0.0f, 0.0f));

	// deleting the auxiliary mesh
	delete meshbox;
	
	return 1;
}

/// function, creating a named plane having specified width and height at pos
int create_plane(Object &OM, string name, double width, double height, Vec3 pos)
{

	// creating an auxiliary mesh with a plane surface	
	Mesh meshplane = new Mesh();
	meshplane.addPlaneSurface("plane_surface", width, height, 1.0f);

	// creating a static mesh object, copying a mesh from the auxiliary one and setting parameters
	OM = new ObjectMeshStatic(meshplane);
	OM.setWorldTransform(translate(pos));
	OM.setMaterial("mesh_base", "*");
	OM.setMaterialParameter("albedo_color", Vec4(0.0f, 0.0f, 1.0f, 1.0f), 0);
	OM.setProperty("surface_base", "*");
	OM.setName(name);	

	// deleting the auxiliary mesh	
	delete meshplane;
	
	return 1;
}

int init() {
	
	// setting up player
	Player player = new PlayerSpectator();
	player.setPosition(Vec3(0.0f, -6.0f, 12.5f));
	player.setDirection(Vec3(0.0f, 1.0f, -0.4f));
	engine.game.setPlayer(player);

	// creating a scene: two boxes and a plane
	create_box(box1, "Box 1", Vec4(1.0f, 1.0f, 0.0f, 1.0f), Vec3(0.5f), Vec3(1.5f, 0.0f, 12.0f));
	create_box(box2, "Box 2", Vec4(1.0f, 0.5f, 0.1f, 1.0f), Vec3(0.5f), Vec3(-1.5f, 0.0f, 12.0f));
	create_plane(plane, "Plane", 10.0f, 6.0f, Vec3(0.0f, 1.0f, 10.5f));

	// setting shape collision mask for the first box  [00000000000000000000000000000010]
	box1.getBody().getShape(0).setCollisionMask(2);

	// setting shape collision mask for the second box  [00000000000000000000000000000001]	
	box2.getBody().getShape(0).setCollisionMask(1);
	
	// setting collision mask for the plane surface  [00000000000000000000000000000010]
	plane.setCollisionMask(2, 0);
	
	return 1;
}			

int shutdown() {

	// memory cleanup
	delete box1;
	delete box2;
	delete plane;
	
	return 1;
}
Last update: 2017-07-03