Three.js ShaderMaterial: Raymarching 3D SDF Models with Matcap Mapping

{"title": "Three.js ShaderMaterial: Raymarching 3D SDF Models with Matcap Mapping", "description": "Learn how to implement raymarching in Three.js to render 3D SDF models and apply Matcap textures for realistic surface shading. This comprehensive guide covers shader creation, SDF definition, and rendering techniques.", "keywords": "Three.js, raymarching, SDF, signed distance field, Matcap, shader, fragment shader, vertex shader, 3D graphics, WebGL, rendering", "content": "To render 3D SDF models using Raymarching in Three.js and apply a Matcap texture to them, follow these steps:\n\n1. Create a basic Three.js scene: This includes setting up a camera, renderer, and light source.\n\njavascript\nconst scene = new THREE.Scene();\nconst camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);\nconst renderer = new THREE.WebGLRenderer();\nrenderer.setSize(window.innerWidth, window.innerHeight);\ndocument.body.appendChild(renderer.domElement);\n\nconst light = new THREE.PointLight(0xffffff, 1);\nlight.position.set(1, 1, 1);\nscene.add(light);\n\n\n2. Create a custom ShaderMaterial: Define vertex and fragment shaders within the material. The fragment shader will implement the Raymarching algorithm.\n\njavascript\nconst material = new THREE.ShaderMaterial({\n vertexShader: document.getElementById('vertexShader').textContent,\n fragmentShader: document.getElementById('fragmentShader').textContent\n});\n\n\n3. Write vertex and fragment shaders: The vertex shader passes vertex data to the fragment shader, while the fragment shader performs Raymarching and renders the model.\n\njavascript\n// vertexShader\nvarying vec2 vUv;\nvoid main() {\n vUv = uv;\n gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);\n}\n\n// fragmentShader\nuniform vec2 resolution;\nuniform float time;\nvarying vec2 vUv;\n\nfloat raymarch(vec3 origin, vec3 direction) {\n float t = 0.0;\n for (int i = 0; i < 100; i++) {\n vec3 p = origin + t * direction;\n float d = sdf(p); // Calculate SDF value\n if (d < 0.001) {\n return t;\n }\n t += d;\n }\n return -1.0;\n}\n\nvec3 getNormal(vec3 p) {\n float d = sdf(p);\n vec3 e = vec3(0.001, 0.0, 0.0);\n return normalize(vec3(\n sdf(p + e.xyy) - d,\n sdf(p + e.yxy) - d,\n sdf(p + e.yyx) - d\n ));\n}\n\nvoid main() {\n vec2 p = (2.0 * gl_FragCoord.xy - resolution) / min(resolution.x, resolution.y);\n vec3 direction = normalize(vec3(p, -1.0));\n vec3 origin = vec3(0.0, 0.0, 3.0);\n float t = raymarch(origin, direction);\n if (t > 0.0) {\n vec3 p = origin + t * direction;\n vec3 n = getNormal(p);\n vec3 lightDir = normalize(light.position - p);\n float diffuse = max(dot(n, lightDir), 0.0);\n vec3 color = vec3(1.0, 0.0, 0.0) * diffuse; // Set model color\n gl_FragColor = vec4(color, 1.0);\n } else {\n gl_FragColor = vec4(0.0);\n }\n}\n\n\n4. Update uniforms in the render loop and render the scene:\n\njavascript\nfunction animate() {\n requestAnimationFrame(animate);\n\n material.uniforms.resolution.value.x = window.innerWidth;\n material.uniforms.resolution.value.y = window.innerHeight;\n material.uniforms.time.value += 0.01;\n\n renderer.render(scene, camera);\n}\nanimate();\n\n\n5. Add vertex and fragment shader code to your HTML file and include the Three.js library:\n\nhtml\n<!-- HTML -->\n<script id="vertexShader" type="x-shader/x-vertex">\n // vertexShader code\n</script>\n<script id="fragmentShader" type="x-shader/x-fragment">\n // fragmentShader code\n</script>\n<script src="https://threejs.org/build/three.min.js"></script>\n\n\nNow you can render 3D SDF models using Raymarching in Three.js, and apply Matcap textures to them. Remember to modify the SDF function, model color, and other parameters in the shaders based on your needs.\n\nThis guide provides a basic framework for using Raymarching in Three.js with SDF models. You can expand upon this foundation by adding features like dynamic lighting, textures, and more complex SDF geometries to achieve visually stunning results.\n