add GeometryHelper

thermion_dart/lib/thermion_dart/geometry_helper.dart

@@ -0,0 +1,145 @@
+import 'dart:math';
+
+class Geometry {
+  final List<double> vertices;
+  final List<int> indices;
+  final List<double> normals;
+
+  Geometry(this.vertices, this.indices, this.normals);
+}
+
+class GeometryHelper {
+  static Geometry sphere() {
+    int latitudeBands = 20;
+    int longitudeBands = 20;
+
+    List<double> vertices = [];
+    List<double> normals = [];
+    List<int> indices = [];
+
+    for (int latNumber = 0; latNumber <= latitudeBands; latNumber++) {
+      double theta = latNumber * pi / latitudeBands;
+      double sinTheta = sin(theta);
+      double cosTheta = cos(theta);
+
+      for (int longNumber = 0; longNumber <= longitudeBands; longNumber++) {
+        double phi = longNumber * 2 * pi / longitudeBands;
+        double sinPhi = sin(phi);
+        double cosPhi = cos(phi);
+
+        double x = cosPhi * sinTheta;
+        double y = cosTheta;
+        double z = sinPhi * sinTheta;
+
+        vertices.addAll([x, y, z]);
+        normals.addAll([x, y, z]); // For a sphere, normals are the same as vertex positions
+      }
+    }
+
+    for (int latNumber = 0; latNumber < latitudeBands; latNumber++) {
+      for (int longNumber = 0; longNumber < longitudeBands; longNumber++) {
+        int first = (latNumber * (longitudeBands + 1)) + longNumber;
+        int second = first + longitudeBands + 1;
+
+        indices.addAll([first, second, first + 1, second, second + 1, first + 1]);
+      }
+    }
+
+    return Geometry(vertices, indices, normals);
+  }
+
+  static Geometry cube() {
+    final vertices = <double>[
+      // Front face
+      -1, -1, 1,
+      1, -1, 1,
+      1, 1, 1,
+      -1, 1, 1,
+
+      // Back face
+      -1, -1, -1,
+      -1, 1, -1,
+      1, 1, -1,
+      1, -1, -1,
+
+      // Top face
+      -1, 1, -1,
+      -1, 1, 1,
+      1, 1, 1,
+      1, 1, -1,
+
+      // Bottom face
+      -1, -1, -1,
+      1, -1, -1,
+      1, -1, 1,
+      -1, -1, 1,
+
+      // Right face
+      1, -1, -1,
+      1, 1, -1,
+      1, 1, 1,
+      1, -1, 1,
+
+      // Left face
+      -1, -1, -1,
+      -1, -1, 1,
+      -1, 1, 1,
+      -1, 1, -1,
+    ];
+
+    final normals = <double>[
+      // Front face
+      0, 0, 1,
+      0, 0, 1,
+      0, 0, 1,
+      0, 0, 1,
+
+      // Back face
+      0, 0, -1,
+      0, 0, -1,
+      0, 0, -1,
+      0, 0, -1,
+
+      // Top face
+      0, 1, 0,
+      0, 1, 0,
+      0, 1, 0,
+      0, 1, 0,
+
+      // Bottom face
+      0, -1, 0,
+      0, -1, 0,
+      0, -1, 0,
+      0, -1, 0,
+
+      // Right face
+      1, 0, 0,
+      1, 0, 0,
+      1, 0, 0,
+      1, 0, 0,
+
+      // Left face
+      -1, 0, 0,
+      -1, 0, 0,
+      -1, 0, 0,
+      -1, 0, 0,
+    ];
+
+    final indices = [
+      // Front face
+      0, 3, 2, 0, 2, 1,
+      // Back face
+      4, 7, 6, 4, 6, 5,
+      // Top face
+      8, 11, 10, 8, 10, 9,
+      // Bottom face
+      12, 15, 14, 12, 14, 13,
+      // Right face
+      16, 19, 18, 16, 18, 17,
+      // Left face
+      20, 23, 22, 20, 22, 21
+    ];
+
+    return Geometry(vertices, indices, normals);
+  }
+}