Integrating Illumination into a ShaderMaterial in three.js

Question

Integrating Illumination into a ShaderMaterial in three.js

I'm exploring the idea of creating a ShaderMaterial with lighting similar to that of a MeshLambertMaterial. To achieve this, I have developed a vertex and fragment shader (available here) and included the uniforms from THREE.ShaderLib[ 'lambert' ].uniforms in the ShaderMaterial.

As far as I understand, the next step would involve merging the code from the fragment and vertex shaders used in the MeshLambertMaterial (fragment and vertex shaders) with my custom shader code for adding lighting.

While combining the vertex shader seems relatively simple, I am unsure how to integrate a base color (generated by my custom shader) into the meshlambert_frag.glsl code for lighting calculations. A potential scenario could resemble the following:

// Custom shader code preceding the main function
// Code from meshlambert_frag.glsl preceding the main function
void main {
  vec4 myBaseColor ... // Generated by custom fragment shader
  // meshlambert_frag.glsl code within the main function will utilize myBaseColor for lighting calculations before setting gl_FragColor
}

Furthermore, is duplicating such a significant portion of code (from meshlambert shaders) deemed bad practice in this context? What alternative approach would you recommend?

javascript three.js shader lighting

Answer 1

Answer №1

To pass a color to the fragment shader code in MeshLambertMaterial, one would typically adjust the diffuseColor variable. This allows setting the color in the fragment shader by using the multiplication operation with aVec3 and diffuseColor.rgb. Here's an example of how the shader code could be structured:

// Vertex Shader
#define LAMBERT

// Include necessary libraries and definitions

varying vec3 vertexColor;
varying vec2 vUv;
varying vec4 worldPosition;

void main() {
   // Define vertex properties and calculations

}

// Fragment Shader
uniform float time;
varying vec2 vUv;

// Define noise functions and other utility operations

varying vec4 worldPosition; 

// Uniforms and varying variables declarations

float sigmoid(float x) {
    return x / (1.0 + abs(x));
}

varying vec3 vertexColor;

void main() {
    // Main logic for fragment shading, including custom effects based on world position

}

In order to streamline your shader code and make it more maintainable, you can consider using shader chunks with THREE.ShaderChunk array in Three.js. By breaking down the MeshLambertMaterial shader into smaller parts and including them using #include directives, you can simplify your custom shader development process. For example, you can define shader chunks like the following for MeshLambert lighting:

THREE.ShaderChunk["meshlambert_premain_fragment"] = `
        // Code snippets for MeshLambertMaterial

`;

Later on, when writing your custom shader that requires MeshLambert lighting, you can simply include the shader chunk to incorporate the functionality without duplicating extensive code:

#include <meshlambert_premain_fragment>

Answer 2

To pass a color to the fragment shader code in MeshLambertMaterial, one would typically adjust the diffuseColor variable. This allows setting the color in the fragment shader by using the multiplication operation with aVec3 and diffuseColor.rgb. Here's an example of how the shader code could be structured:

// Vertex Shader
#define LAMBERT

// Include necessary libraries and definitions

varying vec3 vertexColor;
varying vec2 vUv;
varying vec4 worldPosition;

void main() {
   // Define vertex properties and calculations

}

// Fragment Shader
uniform float time;
varying vec2 vUv;

// Define noise functions and other utility operations

varying vec4 worldPosition; 

// Uniforms and varying variables declarations

float sigmoid(float x) {
    return x / (1.0 + abs(x));
}

varying vec3 vertexColor;

void main() {
    // Main logic for fragment shading, including custom effects based on world position

}

In order to streamline your shader code and make it more maintainable, you can consider using shader chunks with THREE.ShaderChunk array in Three.js. By breaking down the MeshLambertMaterial shader into smaller parts and including them using #include directives, you can simplify your custom shader development process. For example, you can define shader chunks like the following for MeshLambert lighting:

THREE.ShaderChunk["meshlambert_premain_fragment"] = `
        // Code snippets for MeshLambertMaterial

`;

Later on, when writing your custom shader that requires MeshLambert lighting, you can simply include the shader chunk to incorporate the functionality without duplicating extensive code:

#include <meshlambert_premain_fragment>

Integrating Illumination into a ShaderMaterial in three.js

Answer №1

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