Circle Struct

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

Declaration

struct helios::rendering::asset::shape::basic::Circle { ... }

Base struct

struct	Shape
	Struct representing geometric primitives and indices for various shapes. provides immutable, shared access to vertices and indices of the represented geometric shape. More...

Public Constructors Index

	Circle ()
	Creates a default circle (radius 1.0, 64 segments). More...
	Circle (float radius, unsigned int segments)
	Creates a circle with a specific radius and segment count. More...

Public Member Functions Index

helios::rendering::model::config::PrimitiveType	primitiveType () const noexcept override
	Returns the intended PrimitiveType for this Shape. More...

Private Static Functions Index

static std::vector< Vertex >	generateVertices (float radius, unsigned int segments)
	Dynamically creates the vertex list for a circle. Generates one center vertex (Index 0) and 'segments' vertices on the circumference. More...
static std::vector< unsigned int >	generateIndices (unsigned int segments)
	Creates the index list for a `Triangle Fan` (for GL_TRIANGLES). Each triangle consists of (center, point_i, point_i+1). More...

Description

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

Generates a 2D circle mesh, centered at the origin on the XY plane (Z=0). The normals point in the positive Z direction. The indices are arranged as a Triangle Fan (for GL_TRIANGLES).

Definition at line 29 of file Circle.ixx.

Public Constructors

Circle()

helios::rendering::asset::shape::basic::Circle::Circle ()

inline

Creates a default circle (radius 1.0, 64 segments).

Definition at line 94 of file Circle.ixx.

94 Circle() : Circle(1.0f, 64) {}

Reference Circle.

Referenced by Circle.

Circle()

helios::rendering::asset::shape::basic::Circle::Circle (float radius, unsigned int segments)

inline explicit

Creates a circle with a specific radius and segment count.

Parameters

radius	The radius of the circle (from center to circumference).
segments	The number of triangle segments that make up the circle. (More segments = smoother circle).

Definition at line 103 of file Circle.ixx.

103 explicit Circle(float radius, unsigned int segments) :

104 Shape(

105 generateVertices(radius, segments),

106 generateIndices(segments)

107 ) {}

Reference helios::rendering::asset::shape::Shape::Shape.

Public Member Functions

primitiveType()

helios::rendering::model::config::PrimitiveType helios::rendering::asset::shape::basic::Circle::primitiveType ()

inline nodiscard noexcept virtual

Returns the intended PrimitiveType for this Shape.

This method returns the intended PrimitiveType for the Shape represented by this instance. This information can be used to properly set up the MeshConfig wrapping this Shape.

Returns

The intended PrimitiveType of this Shape.

Definition at line 109 of file Circle.ixx.

109 [[nodiscard]] helios::rendering::model::config::PrimitiveType primitiveType() const noexcept override {

110 return model::config::PrimitiveType::Triangles;

111 }

Reference helios::rendering::model::config::Triangles.

Private Static Functions

generateIndices()

std::vector< unsigned int > helios::rendering::asset::shape::basic::Circle::generateIndices (unsigned int segments)

inline static

Creates the index list for a `Triangle Fan` (for GL_TRIANGLES). Each triangle consists of (center, point_i, point_i+1).

Definition at line 73 of file Circle.ixx.

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 }

generateVertices()

std::vector< Vertex > helios::rendering::asset::shape::basic::Circle::generateVertices (float radius, unsigned int segments)

inline static

Dynamically creates the vertex list for a circle. Generates one center vertex (Index 0) and 'segments' vertices on the circumference.

Definition at line 36 of file Circle.ixx.

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 }

---

The documentation for this struct was generated from the following file:

• Circle.ixx

---

Generated via doxygen2docusaurus 2.0.0 by Doxygen 1.15.0.