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Calc normal from vertex
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| //https://observablehq.com/@k9/calculating-normals-for-distorted-vertices | |
| varying vec3 vNormal; | |
| uniform float offset; | |
| float tangentFactor = 0.1; | |
| ${perlin()} | |
| // http://lolengine.net/blog/2013/09/21/picking-orthogonal-vector-combing-coconuts | |
| vec3 orthogonal(vec3 v) { | |
| return normalize(abs(v.x) > abs(v.z) ? vec3(-v.y, v.x, 0.0) | |
| : vec3(0.0, -v.z, v.y)); | |
| } | |
| // Any function can go here to distort p | |
| vec3 distorted(vec3 p) { | |
| return p + vec3( | |
| cnoise(p / 3.0 + offset), | |
| cnoise(p / 4.0 + offset + 1.0), | |
| cnoise(p / 5.0 + offset + 2.0) | |
| ); | |
| } | |
| void main() { | |
| vec3 distortedPosition = distorted(position); | |
| vec3 tangent1 = orthogonal(normal); | |
| vec3 tangent2 = normalize(cross(normal, tangent1)); | |
| vec3 nearby1 = position + tangent1 * tangentFactor; | |
| vec3 nearby2 = position + tangent2 * tangentFactor; | |
| vec3 distorted1 = distorted(nearby1); | |
| vec3 distorted2 = distorted(nearby2); | |
| vec4 mvPosition = modelViewMatrix * vec4(distortedPosition, 1.0); | |
| gl_Position = projectionMatrix * mvPosition; | |
| vNormal = normalize(cross(distorted1 - distortedPosition, distorted2 - distortedPosition)); | |
| } |
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