creating a spherical image mapping with three.js

Question

creating a spherical image mapping with three.js

I am currently facing a challenge in UV mapping a cube-map texture onto a sphere. The process of mapping a cube-map onto a cube was straightforward for me. I successfully mapped an image onto a cube using the following steps: Click here to open the image

Here is the final output, showcasing a different image of the same type [Click here to open the Output]

This is the method I used for UV mapping in this particular task:

var geometry = new THREE.CubeGeometry( 10, 10, 10); 
 
var material = new THREE.MeshPhongMaterial( { map:THREE.ImageUtils.loadTexture('images/texture-atlas.jpg') } );

While I found some resources for OpenGL, the information available for Three.js was limited.

If you have any suggestions or tips that could assist me in completing this task successfully, I would greatly appreciate it. If feasible, please guide me on how to map one image onto the corresponding part of the sphere, and I will replicate the process for the remaining parts.

javascript three.js

Answer 1

Answer №1

Transforming a SphereGeometry to achieve a specific mapping may not be directly possible due to the vertex locations. However, you can achieve the desired result by morphing a BoxGeometry into a sphere.

// Create a box geometry
var geometry = new THREE.BoxGeometry( 10, 10, 10, 8, 8, 8 );

// Morph the box into a sphere
for ( var i = 0; i < geometry.vertices.length; i ++ ) {

    geometry.vertices[ i ].normalize().multiplyScalar( 10 ); // Adjust size as needed

}

// Define repeat and offsets for texture mapping
var repeat = new THREE.Vector2( 1/3, 1/2 );
var offsets = [ 
    new THREE.Vector2( 0, 0 ),
    new THREE.Vector2( 0, 1/2 ),
    new THREE.Vector2( 1/3, 0 ),
    new THREE.Vector2( 1/3, 1/2 ),
    new THREE.Vector2( 2/3, 0 ),
    new THREE.Vector2( 2/3, 1/2 )
];

// Adjust vertex normals for a sphere and reset UVs
for ( var i = 0; i < geometry.faces.length; i ++ ) {

    var face = geometry.faces[ i ];

    face.vertexNormals[ 0 ].copy( geometry.vertices[ face.a ] ).normalize();
    face.vertexNormals[ 1 ].copy( geometry.vertices[ face.b ] ).normalize();
    face.vertexNormals[ 2 ].copy( geometry.vertices[ face.c ] ).normalize();

    var uvs = geometry.faceVertexUvs[ 0 ];

    for ( var j = 0; j < 3; j ++ ) {

        uvs[ i ][ j ].multiply( repeat ).add( offsets[ face.materialIndex ] );

    }

}

var loader = new THREE.TextureLoader();
var texture = loader.load( 'texture.jpg' );

// Create a mesh with the modified geometry and apply texture
var mesh = new THREE.Mesh( geometry, new THREE.MeshPhongMaterial( { map: texture } ) );
scene.add( mesh );

Using three.js r.77

Answer 2

Transforming a SphereGeometry to achieve a specific mapping may not be directly possible due to the vertex locations. However, you can achieve the desired result by morphing a BoxGeometry into a sphere.

// Create a box geometry
var geometry = new THREE.BoxGeometry( 10, 10, 10, 8, 8, 8 );

// Morph the box into a sphere
for ( var i = 0; i < geometry.vertices.length; i ++ ) {

    geometry.vertices[ i ].normalize().multiplyScalar( 10 ); // Adjust size as needed

}

// Define repeat and offsets for texture mapping
var repeat = new THREE.Vector2( 1/3, 1/2 );
var offsets = [ 
    new THREE.Vector2( 0, 0 ),
    new THREE.Vector2( 0, 1/2 ),
    new THREE.Vector2( 1/3, 0 ),
    new THREE.Vector2( 1/3, 1/2 ),
    new THREE.Vector2( 2/3, 0 ),
    new THREE.Vector2( 2/3, 1/2 )
];

// Adjust vertex normals for a sphere and reset UVs
for ( var i = 0; i < geometry.faces.length; i ++ ) {

    var face = geometry.faces[ i ];

    face.vertexNormals[ 0 ].copy( geometry.vertices[ face.a ] ).normalize();
    face.vertexNormals[ 1 ].copy( geometry.vertices[ face.b ] ).normalize();
    face.vertexNormals[ 2 ].copy( geometry.vertices[ face.c ] ).normalize();

    var uvs = geometry.faceVertexUvs[ 0 ];

    for ( var j = 0; j < 3; j ++ ) {

        uvs[ i ][ j ].multiply( repeat ).add( offsets[ face.materialIndex ] );

    }

}

var loader = new THREE.TextureLoader();
var texture = loader.load( 'texture.jpg' );

// Create a mesh with the modified geometry and apply texture
var mesh = new THREE.Mesh( geometry, new THREE.MeshPhongMaterial( { map: texture } ) );
scene.add( mesh );

Using three.js r.77

creating a spherical image mapping with three.js

Answer №1

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