Using cannonjs and Three.js to connect a physics body with a visual mesh

Question

Using cannonjs and Three.js to connect a physics body with a visual mesh

I have written the code below to create two spheres using cannonjs with Three.js for rendering.

var world, mass, body, shape, timeStep=1/60,
    camera, scene, renderer, geometry, material, mesh;
    initThree();
    initCannon();
    animate();

    function initCannon() {
        // Code for initializing Cannon physics
    }

    function initThree() {
        // Code for initializing Three.js graphics
    }

    function animate() {
        // Animation loop
    }

    function updatePhysics() {
        // Update physics
    }

    function render() {
        // Render scene
    }

When I run this code, only the second sphere animates while the first one remains static. The association between the cannonjs body and Three.js mesh seems to be off. I tried adding "body.mesh=mesh", but it didn't solve the issue.

The mesh declaration was originally in initThree(), but I'm unsure if that is causing the problem.

Can someone please help me figure out what I am doing wrong? Let me know if you need more details.

javascript three.js physics-engine

Answer 1

Answer №1

When working with variables, it's important to avoid overwriting them unintentionally. For example, declaring a variable body and then assigning it a new value with body = new CANNON.Body... can lead to the original data being overwritten. To prevent this, consider using distinct variable names like body2 and mesh2 for additional objects.

If you anticipate needing multiple bodies, a more efficient approach is to use Arrays. By storing all bodies in an Array, you can easily iterate through each one individually. For instance:

var bodies = []; // create an array

for (var i = 0; i < 10; i++) {
    bodies.push({ 
        body: new CANNON.Body({mass:0.2}),
        mesh: new THREE.Mesh(geometry, material)
    })
};

Subsequently, you can manipulate each body within the Array using a loop:

for (var i=0, l=bodies.length; i < l; i++) { 
    var body = bodies[i]; 
    // Perform operations on each individual body here
}

This method is more scalable and manageable, allowing you to work with as many bodies as needed without encountering conflicts. In cases where only two bodies are required, simply introducing a separate variable for the second body could provide a quick solution.

Additional resource: https://www.youtube.com/watch?v=tW6pmzd34Hc. This video demonstrates storing circles in an array for clearer understanding.

Answer 2

When working with variables, it's important to avoid overwriting them unintentionally. For example, declaring a variable body and then assigning it a new value with body = new CANNON.Body... can lead to the original data being overwritten. To prevent this, consider using distinct variable names like body2 and mesh2 for additional objects.

If you anticipate needing multiple bodies, a more efficient approach is to use Arrays. By storing all bodies in an Array, you can easily iterate through each one individually. For instance:

var bodies = []; // create an array

for (var i = 0; i < 10; i++) {
    bodies.push({ 
        body: new CANNON.Body({mass:0.2}),
        mesh: new THREE.Mesh(geometry, material)
    })
};

Subsequently, you can manipulate each body within the Array using a loop:

for (var i=0, l=bodies.length; i < l; i++) { 
    var body = bodies[i]; 
    // Perform operations on each individual body here
}

This method is more scalable and manageable, allowing you to work with as many bodies as needed without encountering conflicts. In cases where only two bodies are required, simply introducing a separate variable for the second body could provide a quick solution.

Additional resource: https://www.youtube.com/watch?v=tW6pmzd34Hc. This video demonstrates storing circles in an array for clearer understanding.

Using cannonjs and Three.js to connect a physics body with a visual mesh

Answer №1

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