82 lines
2.3 KiB
Kotlin
82 lines
2.3 KiB
Kotlin
package org.openrndr.extras.meshgenerators
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import org.openrndr.draw.VertexBuffer
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import org.openrndr.math.Vector2
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import org.openrndr.math.Vector3
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import kotlin.math.sqrt
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// Based on
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// https://github.com/mrdoob/three.js/blob/master/src/geometries/DodecahedronGeometry.js
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// Create:
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// val dode = dodecahedronMesh(400.0)
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// Draw:
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// drawer.vertexBuffer(dode, DrawPrimitive.TRIANGLES)
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fun dodecahedronMesh(radius: Double = 1.0): VertexBuffer {
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val vb = meshVertexBuffer(12 * 3 * 3)
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vb.put {
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generateDodecahedron(radius, bufferWriter(this))
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}
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return vb
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}
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fun generateDodecahedron(radius: Double = 1.0, writer: VertexWriter) {
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val t = (1.0 + sqrt(5.0)) / 2;
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val r = 1 / t;
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val vertices = listOf(
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// (±1, ±1, ±1)
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-1.0, -1.0, -1.0, -1.0, -1.0, 1.0,
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-1.0, 1.0, -1.0, -1.0, 1.0, 1.0,
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1.0, -1.0, -1.0, 1.0, -1.0, 1.0,
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1.0, 1.0, -1.0, 1.0, 1.0, 1.0,
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// (0, ±1/φ, ±φ)
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0.0, -r, -t, 0.0, -r, t,
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0.0, r, -t, 0.0, r, t,
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// (±1/φ, ±φ, 0)
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-r, -t, 0.0, -r, t, 0.0,
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r, -t, 0.0, r, t, 0.0,
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// (±φ, 0, ±1/φ)
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-t, 0.0, -r, t, 0.0, -r,
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-t, 0.0, r, t, 0.0, r
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);
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val indices = listOf(
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3, 11, 7, 3, 7, 15, 3, 15, 13,
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7, 19, 17, 7, 17, 6, 7, 6, 15,
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17, 4, 8, 17, 8, 10, 17, 10, 6,
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8, 0, 16, 8, 16, 2, 8, 2, 10,
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0, 12, 1, 0, 1, 18, 0, 18, 16,
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6, 10, 2, 6, 2, 13, 6, 13, 15,
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2, 16, 18, 2, 18, 3, 2, 3, 13,
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18, 1, 9, 18, 9, 11, 18, 11, 3,
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4, 14, 12, 4, 12, 0, 4, 0, 8,
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11, 9, 5, 11, 5, 19, 11, 19, 7,
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19, 5, 14, 19, 14, 4, 19, 4, 17,
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1, 12, 14, 1, 14, 5, 1, 5, 9
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);
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// TODO: assign texture uv coordinates
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// cylindrical? spherical?
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// billboarding pentagons?
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// unwrap?
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val uv = Vector2(0.0)
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val ii = indices.iterator()
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while (ii.hasNext()) {
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val tri = List(3) {
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val i = ii.next()
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Vector3(vertices[i * 3],
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vertices[i * 3 + 1],
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vertices[i * 3 + 2]) * radius
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}
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val up = (tri[1] - tri[0]).cross(tri[2] - tri[0]).normalized;
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writer(tri[0], up, uv)
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writer(tri[1], up, uv)
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writer(tri[2], up, uv)
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}
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} |