Skip to main content

Circle.ixx File

Basic circle shape for rendering. More...

Included Headers​

#include <vector> #include <cmath> #include <numbers> #include <helios.rendering.mesh.PrimitiveType> #include <helios.math.types> #include <helios.rendering.Vertex> #include <helios.rendering.asset.shape.Shape>

Namespaces Index​

namespacehelios
namespacerendering

Graphics rendering infrastructure. More...

namespaceasset

Rendering asset management. More...

namespaceshape

Geometric shape definitions. More...

namespacebasic

Basic primitive shapes. More...

Classes Index​

structCircle

Basic Circle Shape (2D, in XY plane). More...

Description​

Basic circle shape for rendering.

File Listing​

The file content with the documentation metadata removed is:

1/**
2 * @file Circle.ixx
3 * @brief Basic circle shape for rendering.
4 */
5module;
6
7#include <vector>
8#include <cmath>
9#include <numbers>
10
11export module helios.rendering.asset.shape.basic.Circle;
12
13import helios.rendering.asset.shape.Shape;
14import helios.rendering.Vertex;
15import helios.math.types;
16import helios.rendering.mesh.PrimitiveType;
17
18using namespace helios::rendering;
19
20export namespace helios::rendering::asset::shape::basic {
21
22 /**
23 * @brief Basic Circle Shape (2D, in XY plane).
24 *
25 * Generates a 2D circle mesh, centered at the origin on the XY plane (Z=0).
26 * The normals point in the positive Z direction.
27 * The indices are arranged as a Triangle Fan (for GL_TRIANGLES).
28 */
29 struct Circle : public Shape {
30
31 private:
32 /**
33 * @brief Dynamically creates the vertex list for a circle.
34 * Generates one center vertex (Index 0) and 'segments' vertices on the circumference.
35 */
36 static std::vector<Vertex> generateVertices(float radius, unsigned int segments) {
37 std::vector<Vertex> vertices;
38 // 1 for the center vertex
39 vertices.reserve(segments + 1);
40
41 // center vertex (index 0)
42 vertices.push_back({
43 {0.0f, 0.0f, 0.0f}, // Position
44 {0.0f, 0.0f, 1.0f}, // Normal
45 {0.5f, 0.5f} // TexCoord
46 });
47
48 // circumference vertices (Indices 1 to segments)
49 for (unsigned int i = 0; i < segments; ++i) {
50 // calculate the angle for this segment
51 const float angle = (static_cast<float>(i) / static_cast<float>(segments)) * 2.0f * std::numbers::pi_v<float>;
52
53 float x = radius * std::cos(angle);
54 float y = radius * std::sin(angle);
55
56 // texture coordinates: map [-radius, +radius] to [0, 1]
57 float u = (x / radius) * 0.5f + 0.5f;
58 float v = (y / radius) * 0.5f + 0.5f;
59
60 vertices.push_back({
61 {x, y, 0.0f},
62 {0.0f, 0.0f, 1.0f},
63 {u, v}
64 });
65 }
66 return vertices;
67 }
68
69 /**
70 * @brief Creates the index list for a `Triangle Fan` (for GL_TRIANGLES).
71 * Each triangle consists of (center, point_i, point_i+1).
72 */
73 static std::vector<unsigned int> generateIndices(unsigned int segments) {
74 std::vector<unsigned int> indices;
75 indices.reserve(segments * 3); // 'segments' triangles, 3 indices per triangle
76
77 for (unsigned int i = 1; i <= segments; ++i) {
78 indices.push_back(0); // center vertex
79 indices.push_back(i); // current circumference vertex
80
81 // next circumference vertex
82 // for the last triangle (i == segments),
83 // connect back to Vertex 1
84 unsigned int next_i = (i == segments) ? 1 : (i + 1);
85 indices.push_back(next_i);
86 }
87 return indices;
88 }
89
90 public:
91 /**
92 * @brief Creates a default circle (radius 1.0, 64 segments).
93 */
94 Circle() : Circle(1.0f, 64) {}
95
96 /**
97 * @brief Creates a circle with a specific radius and segment count.
98 *
99 * @param radius The radius of the circle (from center to circumference).
100 * @param segments The number of triangle segments that make up the circle.
101 * (More segments = smoother circle).
102 */
103 explicit Circle(float radius, unsigned int segments) :
104 Shape(
105 generateVertices(radius, segments),
106 generateIndices(segments)
107 ) {}
108
109 [[nodiscard]] helios::rendering::mesh::PrimitiveType primitiveType() const noexcept override {
110 return mesh::PrimitiveType::Triangles;
111 }
112 };
113
114}

Generated via doxygen2docusaurus 2.0.0 by Doxygen 1.15.0.