How can I include a custom shader reference in the json material format in three.js?

Question

How can I include a custom shader reference in the json material format in three.js?

For those using the JSON Object Scene format 4 for Three.js, there is a specification for materials that can be found here.

However, it seems unclear whether it is possible to reference a custom shader from this specification. Does anyone have any insights on how this could be achieved?

[UPDATE]

Upon reflection, it appears my initial question may not have been clear enough. What I'm really trying to figure out is how to make the JSON loader interpret a material defined by a custom shader within the JSON Object Scene format 4:

"materials": [
    {
        "uuid": "87D95D6C-6BB4-4B8F-8166-A3A6945BA5E3",
        "type": "MeshPhongMaterial",
        "color": 16777215,
        "ambient": 16777215,
        "emissive": 0,
        "specular": 1118481,
        "shininess": 30,
        "opacity": 1,
        "transparent": false,
        "wireframe": false
    }
],
"object": {
    "uuid": "89529CC6-CBAC-412F-AFD1-FEEAE785BA19",
    "type": "Scene",
    "matrix": [1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1],
    "children": [
        {
            "uuid": "33FA38D9-0AAC-4657-9BBE-5E5780DDFB2F",
            "name": "Box 1",
            "type": "Mesh",
            "geometry": "C3BF1E70-0BE7-4E6D-B184-C9F1E84A3423",
            "material": "87D95D6C-6BB4-4B8F-8166-A3A6945BA5E3",
            "matrix": [1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1]
        },

In this excerpt, a mesh references a material by its UUID. The issue lies in the fact that the types of materials are predetermined within the WebGLPrograms function, making it challenging to expand this list with a custom shader.

javascript three.js shader

Answer 1

Answer №1

To create a custom shader, you need to develop either a ShaderMaterial or a RawShaderMaterial by specifying the attributes vertexShader and fragmentShader, with both shader codes included in the HTML/JS source.

If you provide the source for both shaders in JSON format, a ShaderMaterial can inherit from the base Material object.

A default vertex and fragment shader code will be visible in the JSON output when using a parameter-less ShaderMaterial.

var shader = new THREE.ShaderMaterial();
console.log(shader.toJSON());

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r82/three.js" charset="utf-8"></script>

Update:

After further review, it appears that creating an instance of a custom ShaderMaterial may not be straightforward or clearly defined.

The MaterialLoader is capable of loading a ShaderMaterial with customized vertex and fragment shaders, ensuring compatibility between the Material.toJSON method and the MaterialLoader.

// Ensuring consistency in saving and loading
var loader = new THREE.MaterialLoader();

var shaderMaterial = new THREE.ShaderMaterial();
var shaderMaterialJSON = JSON.stringify(shaderMaterial.toJSON());

console.log('JSON ' + shaderMaterialJSON);

var loadedShaderMaterial = loader.parse(JSON.parse(shaderMaterialJSON));

console.log(loadedShaderMaterial);

// Converting a phong material to a shader material
var phongMatJSON = '{"uuid": "87D95D6C-6BB4-4B8F-8166-A3A6945BA5E3", "type": "MeshPhongMaterial", "color": 16777215, "ambient": 16777215, "emissive": 0, "specular": 1118481, "shininess": 30, "opacity": 1, "transparent": false, "wireframe": false}';

var phongMatObj = JSON.parse(phongMatJSON);
phongMatObj.color = undefined; // Not used in ShaderMaterial
phongMatObj.emissive = undefined; // Not used in ShaderMaterial
phongMatObj.specular = undefined; // Not used in ShaderMaterial
phongMatObj.name = '';
phongMatObj.type = 'ShaderMaterial';
phongMatObj.uniforms = {};
phongMatObj.vertexShader = 'void main() {\n\tgl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n}';
phongMatObj.fragmentShader = 'void main() {\n\tgl_FragColor = vec4( 0.0, 0.0, 1.0, 1.0 );\n}';

var shaderMatObj = loader.parse(phongMatObj);

console.log(shaderMatObj);

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r82/three.js" charset="utf-8"></script>

Answer 2

To create a custom shader, you need to develop either a ShaderMaterial or a RawShaderMaterial by specifying the attributes vertexShader and fragmentShader, with both shader codes included in the HTML/JS source.

If you provide the source for both shaders in JSON format, a ShaderMaterial can inherit from the base Material object.

A default vertex and fragment shader code will be visible in the JSON output when using a parameter-less ShaderMaterial.

var shader = new THREE.ShaderMaterial();
console.log(shader.toJSON());

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r82/three.js" charset="utf-8"></script>

Update:

After further review, it appears that creating an instance of a custom ShaderMaterial may not be straightforward or clearly defined.

The MaterialLoader is capable of loading a ShaderMaterial with customized vertex and fragment shaders, ensuring compatibility between the Material.toJSON method and the MaterialLoader.

// Ensuring consistency in saving and loading
var loader = new THREE.MaterialLoader();

var shaderMaterial = new THREE.ShaderMaterial();
var shaderMaterialJSON = JSON.stringify(shaderMaterial.toJSON());

console.log('JSON ' + shaderMaterialJSON);

var loadedShaderMaterial = loader.parse(JSON.parse(shaderMaterialJSON));

console.log(loadedShaderMaterial);

// Converting a phong material to a shader material
var phongMatJSON = '{"uuid": "87D95D6C-6BB4-4B8F-8166-A3A6945BA5E3", "type": "MeshPhongMaterial", "color": 16777215, "ambient": 16777215, "emissive": 0, "specular": 1118481, "shininess": 30, "opacity": 1, "transparent": false, "wireframe": false}';

var phongMatObj = JSON.parse(phongMatJSON);
phongMatObj.color = undefined; // Not used in ShaderMaterial
phongMatObj.emissive = undefined; // Not used in ShaderMaterial
phongMatObj.specular = undefined; // Not used in ShaderMaterial
phongMatObj.name = '';
phongMatObj.type = 'ShaderMaterial';
phongMatObj.uniforms = {};
phongMatObj.vertexShader = 'void main() {\n\tgl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n}';
phongMatObj.fragmentShader = 'void main() {\n\tgl_FragColor = vec4( 0.0, 0.0, 1.0, 1.0 );\n}';

var shaderMatObj = loader.parse(phongMatObj);

console.log(shaderMatObj);

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r82/three.js" charset="utf-8"></script>

How can I include a custom shader reference in the json material format in three.js?

Answer №1

Update:

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