I've encountered a scenario where my scene consists of multiple meshes, each with different shapes and sizes.
By looping through each mesh and utilizing geometry.merge(), I successfully created a new mesh from the geometries in the scene.
The challenge arises when attempting to mask the entire mesh with an alphaMask, as each geometry has the material applied individually.
You can view an example of this situation here - https://codepen.io/danlong/pen/KXOObr
function addObjects(scene) {
// merged geomoetry & material
var mergedGeometry = new THREE.Geometry();
var mergedMaterial = new THREE.MeshStandardMaterial({ color: "#444", transparent: true, side: THREE.DoubleSide, alphaTest: 0.5, opacity: 1, roughness: 1 });
// multiple meshes
var geometry = new THREE.IcosahedronGeometry(30, 5);
var material = new THREE.MeshStandardMaterial({ color: "#444" });
var geo1 = new THREE.IcosahedronGeometry(30, 5);
var mesh1 = new THREE.Mesh( geo1, material );
mesh1.position.x = 10;
mesh1.position.y = 10;
mesh1.position.z = 0;
var geo2 = new THREE.IcosahedronGeometry(30, 5);
var mesh2 = new THREE.Mesh( geo2, material );
mesh2.position.x = 20;
mesh2.position.y = 20;
mesh2.position.z = 0;
var geo3 = new THREE.IcosahedronGeometry(30, 5);
var mesh3 = new THREE.Mesh( geo3, material );
mesh3.position.x = 30;
mesh3.position.y = 30;
mesh3.position.z = 0;
// scene.add(mesh1, mesh2, mesh3);
mesh1.updateMatrix();
mergedGeometry.merge(mesh1.geometry, mesh1.matrix);
mesh2.updateMatrix();
mergedGeometry.merge(mesh2.geometry, mesh2.matrix);
mesh3.updateMatrix();
mergedGeometry.merge(mesh3.geometry, mesh3.matrix);
// alpha texture
var image = document.createElement('img');
var alphaMap = new THREE.Texture(image);
image.onload = function() {
alphaMap.needsUpdate = true;
};
image.src = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAgAAAAICAYAAADED76LAAAAGUlEQVQoU2NkYGD4z4AHMP7//x+/gmFhAgCXphP14bko/wAAAABJRU5ErkJggg==';
mergedMaterial.alphaMap = alphaMap;
mergedMaterial.alphaMap.magFilter = THREE.NearestFilter;
mergedMaterial.alphaMap.wrapT = THREE.RepeatWrapping;
mergedMaterial.alphaMap.repeat.y = 1;
// merged geometry with alpha mask
merge1 = new THREE.Mesh(mergedGeometry, mergedMaterial);
merge1.rotation.z = -Math.PI/4;
// merge geometry without alpha mask
var merge2 = new THREE.Mesh(mergedGeometry, material);
merge2.position.x = -100;
merge2.rotation.z = -Math.PI/4;
scene.add(merge1, merge2);
return mesh;
}
The left-side mesh displays the result of merging geometries to which I aim to apply the alphaMask. The right-side mesh demonstrates that instead of applying the map to the entire mesh, it's being applied to each individual geometry within.
My question is whether there exists a method to mask the complete mesh without affecting each individual geometry?
-- three.js r86
EDIT: Efforts to implement a clipping plane on my mesh didn't yield the desired outcome. My goal is to apply an alphaMask across the entire mesh, unveiling it based on the mask image used. A visual representation of this desired effect can be viewed here - https://codepen.io/supah/pen/zwJxdb
Could the UV mapping of the original geometries play a role in this issue? Is there a need to modify them in any specific manner?