// Create a simulation world
var world = new gp.World({
    renderer: threejsRenderer,            // Must be a THREE.WebGLRenderer
    maxBodies: 128 * 128,                 // Max number of bodies
    maxParticles: 128 * 128,              // Max number of particles (each body consists of a number of particles)
    radius: 0.05,                         // Size of a particle in the simulation
    stiffness: 100,                       // Contact stiffness
    damping: 0.4,                         // Contact damping
    fixedTimeStep: 1/60,                  // Simulation timestep
    boxSize: new THREE.Vector3(10,10,10), // World collision bounds

    // The "grid" is a box where collisions can occur. Specify its position and resolution.
    // The size of the grid box is gridResolution * radius * 2
    gridPosition: new THREE.Vector3(0,0,0),
    gridResolution: new THREE.Vector3(128,16,128),

    gravity: new THREE.Vector3(0,-1,0),
    friction: 0.4,
    drag: 0.3,
});

// Create a body
//                         position   rotation   mass  inertia
var bodyId = world.addBody(0, 0, 0,   0,0,0,1,   1,    0.1,0.1,0.1);
world.addParticle(bodyId, 0,0,0); // Add a particle in the center of the body

// Get the UV coordinate for the body
var uv = world.getBodyUV(bodyId);
myCustomShaderMaterial.uniforms.bodyUV.value = uv;

// A simple render loop can look like this:
var prevTime;
function render(time) {
    requestAnimationFrame(render);
    
    // Calculate time since last frame
    var deltaTime = prevTime ? (time - prevTime) / 1000 : 0;
    prevTime = time;
    
    // Update physics    
    world.step( deltaTime );

    // Use textures from the world, they contain positions and rotations of all bodies.
    // Note: you need to fetch these textures every frame from the World, since they are swapped by the World every step.
    myCustomShaderMaterial.uniforms.bodyPositionTex.value = world.bodyPositionTexture;
    myCustomShaderMaterial.uniforms.bodyQuaternionTex.value = world.bodyQuaternionTexture;

    // Render scene
    renderer.render( scene, camera );
}
requestAnimationFrame(render);