clipTriangles method

void clipTriangles(
  1. Float32List vertices,
  2. int verticesLength,
  3. Int16List triangles,
  4. int trianglesLength,
  5. Float32List uvs,
  6. Color light,
  7. Color dark,
  8. bool twoColor
)

Implementation

void clipTriangles(
    Float32List vertices,
    int verticesLength,
    Int16List triangles,
    int trianglesLength,
    Float32List uvs,
    Color light,
    Color dark,
    bool twoColor) {
  final Float32List clipOutput = this.clipOutput as Float32List,
      clippedVertices = this.clippedVertices as Float32List;
  final Int16List clippedTriangles =
      Int16List.fromList(this.clippedTriangles);
  final List<Float32List>? polygons = clippingPolygons;
  final int polygonsCount = clippingPolygons!.length;
  final int vertexSize = twoColor ? 12 : 8;

  int index = 0;
  clippedVertices.length = 0;
  clippedTriangles.length = 0;
  outer:
  for (int i = 0; i < trianglesLength; i += 3) {
    int vertexOffset = triangles[i] << 1;
    final double x1 = vertices[vertexOffset], y1 = vertices[vertexOffset + 1];
    final double u1 = uvs[vertexOffset], v1 = uvs[vertexOffset + 1];

    vertexOffset = triangles[i + 1] << 1;
    final double x2 = vertices[vertexOffset], y2 = vertices[vertexOffset + 1];
    final double u2 = uvs[vertexOffset], v2 = uvs[vertexOffset + 1];

    vertexOffset = triangles[i + 2] << 1;
    final double x3 = vertices[vertexOffset], y3 = vertices[vertexOffset + 1];
    final double u3 = uvs[vertexOffset], v3 = uvs[vertexOffset + 1];

    for (int p = 0; p < polygonsCount; p++) {
      int s = clippedVertices.length;
      if (clip(x1, y1, x2, y2, x3, y3, polygons![p], clipOutput)) {
        final int clipOutputLength = clipOutput.length;
        if (clipOutputLength == 0) continue;
        final double d0 = y2 - y3, d1 = x3 - x2, d2 = x1 - x3, d4 = y3 - y1;
        final double d = 1 / (d0 * d2 + d1 * (y1 - y3));

        int clipOutputCount = clipOutputLength >> 1;
        final Float32List clipOutputItems = this.clipOutput as Float32List;
        final Float32List clippedVerticesItems =
            ArrayUtils.copyWithNewArraySize(
                clippedVertices,
                s + clipOutputCount * vertexSize,
                double.infinity) as Float32List;
        for (int ii = 0; ii < clipOutputLength; ii += 2) {
          final double x = clipOutputItems[ii], y = clipOutputItems[ii + 1];
          clippedVerticesItems[s] = x;
          clippedVerticesItems[s + 1] = y;
          clippedVerticesItems[s + 2] = light.r;
          clippedVerticesItems[s + 3] = light.g;
          clippedVerticesItems[s + 4] = light.b;
          clippedVerticesItems[s + 5] = light.a;
          final double c0 = x - x3, c1 = y - y3;
          final double a = (d0 * c0 + d1 * c1) * d;
          final double b = (d4 * c0 + d2 * c1) * d;
          final double c = 1 - a - b;
          clippedVerticesItems[s + 6] = u1 * a + u2 * b + u3 * c;
          clippedVerticesItems[s + 7] = v1 * a + v2 * b + v3 * c;
          if (twoColor) {
            clippedVerticesItems[s + 8] = dark.r;
            clippedVerticesItems[s + 9] = dark.g;
            clippedVerticesItems[s + 10] = dark.b;
            clippedVerticesItems[s + 11] = dark.a;
          }
          s += vertexSize;
        }

        s = clippedTriangles.length;
        final Int16List clippedTrianglesItems = Int16List.fromList(
            ArrayUtils.copyWithNewArraySize(
                clippedTriangles, s + 3 * (clipOutputCount - 2), -1));
        clipOutputCount--;
        for (int ii = 1; ii < clipOutputCount; ii++) {
          clippedTrianglesItems[s] = index;
          clippedTrianglesItems[s + 1] = (index + ii);
          clippedTrianglesItems[s + 2] = (index + ii + 1);
          s += 3;
        }
        index += clipOutputCount + 1;
      } else {
        final Float32List clippedVerticesItems =
            ArrayUtils.copyWithNewArraySize(
                    clippedVertices, s + 3 * vertexSize, double.infinity)
                as Float32List;
        clippedVerticesItems[s] = x1;
        clippedVerticesItems[s + 1] = y1;
        clippedVerticesItems[s + 2] = light.r;
        clippedVerticesItems[s + 3] = light.g;
        clippedVerticesItems[s + 4] = light.b;
        clippedVerticesItems[s + 5] = light.a;
        if (!twoColor) {
          clippedVerticesItems[s + 6] = u1;
          clippedVerticesItems[s + 7] = v1;

          clippedVerticesItems[s + 8] = x2;
          clippedVerticesItems[s + 9] = y2;
          clippedVerticesItems[s + 10] = light.r;
          clippedVerticesItems[s + 11] = light.g;
          clippedVerticesItems[s + 12] = light.b;
          clippedVerticesItems[s + 13] = light.a;
          clippedVerticesItems[s + 14] = u2;
          clippedVerticesItems[s + 15] = v2;

          clippedVerticesItems[s + 16] = x3;
          clippedVerticesItems[s + 17] = y3;
          clippedVerticesItems[s + 18] = light.r;
          clippedVerticesItems[s + 19] = light.g;
          clippedVerticesItems[s + 20] = light.b;
          clippedVerticesItems[s + 21] = light.a;
          clippedVerticesItems[s + 22] = u3;
          clippedVerticesItems[s + 23] = v3;
        } else {
          clippedVerticesItems[s + 6] = u1;
          clippedVerticesItems[s + 7] = v1;
          clippedVerticesItems[s + 8] = dark.r;
          clippedVerticesItems[s + 9] = dark.g;
          clippedVerticesItems[s + 10] = dark.b;
          clippedVerticesItems[s + 11] = dark.a;

          clippedVerticesItems[s + 12] = x2;
          clippedVerticesItems[s + 13] = y2;
          clippedVerticesItems[s + 14] = light.r;
          clippedVerticesItems[s + 15] = light.g;
          clippedVerticesItems[s + 16] = light.b;
          clippedVerticesItems[s + 17] = light.a;
          clippedVerticesItems[s + 18] = u2;
          clippedVerticesItems[s + 19] = v2;
          clippedVerticesItems[s + 20] = dark.r;
          clippedVerticesItems[s + 21] = dark.g;
          clippedVerticesItems[s + 22] = dark.b;
          clippedVerticesItems[s + 23] = dark.a;

          clippedVerticesItems[s + 24] = x3;
          clippedVerticesItems[s + 25] = y3;
          clippedVerticesItems[s + 26] = light.r;
          clippedVerticesItems[s + 27] = light.g;
          clippedVerticesItems[s + 28] = light.b;
          clippedVerticesItems[s + 29] = light.a;
          clippedVerticesItems[s + 30] = u3;
          clippedVerticesItems[s + 31] = v3;
          clippedVerticesItems[s + 32] = dark.r;
          clippedVerticesItems[s + 33] = dark.g;
          clippedVerticesItems[s + 34] = dark.b;
          clippedVerticesItems[s + 35] = dark.a;
        }

        s = clippedTriangles.length;
        final Int16List clippedTrianglesItems = Int16List.fromList(
            ArrayUtils.copyWithNewArraySize(clippedTriangles, s + 3, -1));
        clippedTrianglesItems[s] = index;
        clippedTrianglesItems[s + 1] = (index + 1);
        clippedTrianglesItems[s + 2] = (index + 2);
        index += 3;
        continue outer;
      }
    }
  }
}