114 lines
3.7 KiB
JavaScript
114 lines
3.7 KiB
JavaScript
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function mesh (params) {
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const dims = params.dims
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const vertices = []
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const indices = []
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const normals = []
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for (let backFace = true, b = false; b !== backFace; backFace = backFace && b, b = !b) {
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// Sweep over 3-axes
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for (let d = 0; d < 3; ++d) {
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let i, j, k, l, w, h, side
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const u = (d + 1) % 3
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const v = (d + 2) % 3
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const x = [0, 0, 0]
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const q = [0, 0, 0]
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// Here we're keeping track of the side that we're meshing.
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if (d === 0) side = backFace ? LEFT : RIGHT
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else if (d === 1) side = backFace ? BOTTOM : TOP
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else if (d === 2) side = backFace ? BACK : FRONT
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const mask = new Int32Array(dims[u] * dims[v])
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q[d] = 1
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// Move through the dimension from front to back
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for (x[d] = -1; x[d] < dims[d];) {
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// Compute mask
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let n = 0
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for (x[v] = 0; x[v] < dims[v]; ++x[v]) {
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for (x[u] = 0; x[u] < dims[u]; ++x[u]) {
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const current = this.getBlockAt(params, dims, x[0], x[1], x[2])
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const ajacent = this.getBlockAt(params, dims, x[0] + q[0], x[1] + q[1], x[2] + q[2])
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mask[n++] = ((current && ajacent && current === ajacent)) ? null : (backFace ? ajacent : current)
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}
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}
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// Increment x[d]
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++x[d]
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// Generate mesh for mask using lexicographic ordering
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n = 0
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for (j = 0; j < dims[v]; ++j) {
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for (i = 0; i < dims[u];) {
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if (mask[n]) {
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// Compute width
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for (w = 1; mask[n + w] && mask[n + w] === mask[n] && i + w < dims[u]; ++w) {}
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// Compute height
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let done = false
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for (h = 1; j + h < dims[v]; ++h) {
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for (k = 0; k < w; ++k) {
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if (!mask[n + k + h * dims[u]] || mask[n + k + h * dims[u]] !== mask[n]) {
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done = true
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break
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}
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}
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if (done) break
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}
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// Create quad
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x[u] = i
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x[v] = j
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const du = [0, 0, 0]
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du[u] = w
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const dv = [0, 0, 0]
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dv[v] = h
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const quad = [
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[x[0], x[1], x[2]],
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[x[0] + du[0], x[1] + du[1], x[2] + du[2]],
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[x[0] + du[0] + dv[0], x[1] + du[1] + dv[1], x[2] + du[2] + dv[2]],
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[x[0] + dv[0], x[1] + dv[1], x[2] + dv[2]]
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]
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// Add vertices and normals
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const mul = backFace ? -1 : 1
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for (var qindex = 0; qindex < 4; ++qindex) {
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vertices.push(quad[qindex][0], quad[qindex][1], quad[qindex][2])
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normals.push(q[0] * mul, q[1] * mul, q[2] * mul)
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}
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// Add indices
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const indexi = vertices.length / 3 - 4
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if (backFace) {
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indices.push(indexi + 2, indexi + 1, indexi)
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indices.push(indexi + 3, indexi + 2, indexi)
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} else {
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indices.push(indexi, indexi + 1, indexi + 2)
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indices.push(indexi, indexi + 2, indexi + 3)
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}
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// Zero-out mask
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for (l = 0; l < h; ++l) {
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for (k = 0; k < w; ++k) {
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mask[n + k + l * dims[u]] = false
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}
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}
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// Increment counters and continue
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i += w
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n += w
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} else {
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++i
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++n
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}
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}
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}
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}
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}
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}
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return { vertices, indices, normals }
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}
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}
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