A 3D triangle mesh using an indexed face set representation. More...

#include <mesh.h>

Collaboration diagram for scimesh::Mesh:

[legend]

Public Member Functions
bool	has_colors () const
	Does the mesh have per-vertex colors?

bool	has_face_colors () const
	Does the mesh have per-face colors?

bool	has_normals () const
	Does the mesh have per-vertex normals?

bool	has_uvs () const
	Does the mesh have texture coordinates?

bool	has_texture () const
	Does the mesh have a texture image?

bool	has_alpha () const
	Do any of the mesh's colors have alpha < 1.0?

bool	is_transparent () const
	Does the mesh need the alpha-blending pass?

void	update_transparency ()
	Recompute `has_transparency` from the mesh's colors.

bool	is_valid () const
	Check whether the mesh is in a valid, renderable state.

bool	empty () const
	Is the mesh empty (no renderable geometry)?

void	compute_bounding_box (Vec3 &min_bound, Vec3 &max_bound) const
	Compute the axis-aligned bounding box (AABB) of the mesh.

Public Attributes
Required data
std::vector< Vec3 >	vertices
	3D vertex positions.

std::vector< Triangle >	triangles
	Triangle index triplets.

Optional per-vertex data
std::vector< Color >	colors
	Per-vertex RGBA colors.

std::vector< Color >	face_colors
	Per-face RGBA colors.

std::vector< Vec3 >	normals
	Per-vertex surface normals (unit-length direction vectors).

std::vector< Vec2 >	uvs
	Per-vertex texture coordinates (UVs).

Optional texture
Image	texture
	An optional texture image mapped via UV coordinates.

Default appearance
Color	default_color = DEFAULT_COLOR
	Fallback color when no per-vertex or per-face color is set.

bool	has_transparency = false
	Whether the mesh contains any transparent fragments.

Detailed Description

A 3D triangle mesh using an indexed face set representation.

Overview

The Mesh is the heart of scimesh. It holds:

vertices — 3D positions (required)
triangles — which three vertices form each face (required)
colors — per-vertex RGBA colors (optional, for vertex coloring)
face_colors — per-face RGBA colors (optional, for flat face coloring)
normals — per-vertex surface normals (optional, for lighting)
uvs — texture coordinates (optional, for texture mapping)
texture — an Image used as a texture map (optional)

The mesh uses an indexed face set. This means vertices are stored exactly once, and triangles store indices into the vertex array. This saves memory when vertices are shared by multiple triangles.

Construction

There is no special constructor — create an empty mesh and populate it:

Mesh m;
m.vertices = { {0,0,0}, {1,0,0}, {0,1,0} };   // three points
m.triangles = { {0, 1, 2} };                   // one triangle
m.colors = { {1,0,0}, {0,1,0}, {0,0,1} };     // red, green, blue vertices

Or use one of the generator functions:

Mesh sphere = scimesh::generate_sphere({0,0,0}, 1.0f, 32, {0.2f, 0.4f, 0.8f});

scimesh::generate_sphere

Mesh generate_sphere(const Vec3 &center, float radius, int segments, const Color &color)

Generate a UV-sphere (latitude/longitude tessellation).

Definition primitives.cpp:84

Or load from a file:

Mesh brain = scimesh::obj_io::read_obj("/data/brain.obj");

Mesh skull = scimesh::ply_io::read_ply("/data/skull.ply");

scimesh::obj_io::read_obj

Mesh read_obj(const std::string &path)

Load a mesh from a Wavefront OBJ file.

Definition obj_io.cpp:8

scimesh::ply_io::read_ply

Mesh read_ply(const std::string &path)

Load a mesh from a Stanford PLY file.

Definition ply_io.cpp:48

Validation

Call is_valid() before rendering to detect common problems:

missing vertices or triangles
out-of-bounds triangle indices
NaN or infinite vertex positions
mismatched array sizes (e.g., colors but not one per vertex)

See also: generate_sphere(), generate_cuboid(), generate_torus(); read_obj(), read_ply(), read_stl(); Renderer, Triangle, Color

Definition at line 76 of file mesh.h.

Member Function Documentation

◆ compute_bounding_box()

void scimesh::Mesh::compute_bounding_box	(	Vec3 &	min_bound,
		Vec3 &	max_bound
	)		const

inline

Compute the axis-aligned bounding box (AABB) of the mesh.

The bounding box is the smallest box aligned with the X, Y, and Z axes that contains all mesh vertices. Output is written to the two Vec3 reference parameters.

Parameters

[out]	min_bound	The corner with the smallest x, y, z values.
[out]	max_bound	The corner with the largest x, y, z values.

Example: Vec3 bmin, bmax;

mesh.compute_bounding_box(bmin, bmax);

Vec3 center = (bmin + bmax) * 0.5f; // geometric center

Vec3 size = bmax - bmin; // dimensions

scimesh::Vec3
glm::vec3 Vec3
3-component floating-point vector (xyz).
Definition types.h:46

See also: Scene::compute_bounding_box()

Definition at line 350 of file mesh.h.

◆ empty()

bool scimesh::Mesh::empty ( ) const

inline

Is the mesh empty (no renderable geometry)?

Returns: true if there are no vertices or no triangles.

See also: is_valid()

Definition at line 326 of file mesh.h.

◆ has_alpha()

bool scimesh::Mesh::has_alpha ( ) const

inline

Do any of the mesh's colors have alpha < 1.0?

Scans default_color, colors and face_colors. This is a plain query: it does not look at has_transparency.

Returns: true if at least one color is not fully opaque.

See also: is_transparent(), colors, face_colors, default_color

Definition at line 227 of file mesh.h.

◆ has_colors()

bool scimesh::Mesh::has_colors ( ) const

inline

Does the mesh have per-vertex colors?

Returns: true if colors is not empty.

See also: colors

Definition at line 198 of file mesh.h.

◆ has_face_colors()

bool scimesh::Mesh::has_face_colors ( ) const

inline

Does the mesh have per-face colors?

Returns: true if face_colors is not empty.

See also: face_colors

Definition at line 203 of file mesh.h.

◆ has_normals()

bool scimesh::Mesh::has_normals ( ) const

inline

Does the mesh have per-vertex normals?

Returns: true if normals is not empty.

See also: normals, compute_vertex_normals()

Definition at line 208 of file mesh.h.

◆ has_texture()

bool scimesh::Mesh::has_texture ( ) const

inline

Does the mesh have a texture image?

Returns: true if texture.width > 0.

See also: texture, uvs

Definition at line 218 of file mesh.h.

◆ has_uvs()

bool scimesh::Mesh::has_uvs ( ) const

inline

Does the mesh have texture coordinates?

Returns: true if uvs is not empty.

See also: uvs, texture

Definition at line 213 of file mesh.h.

◆ is_transparent()

bool scimesh::Mesh::is_transparent ( ) const

inline

Does the mesh need the alpha-blending pass?

True when has_transparency is set manually, or when any color (or default_color) has alpha < 1.0. The renderer asks this instead of requiring you to keep has_transparency in sync, so per-vertex, per-face and uniform transparency all work out of the box.

Returns: true if the mesh contains translucent fragments.

See also: has_alpha(), update_transparency(), has_transparency

Definition at line 248 of file mesh.h.

◆ is_valid()

bool scimesh::Mesh::is_valid ( ) const

inline

Check whether the mesh is in a valid, renderable state.

This performs several checks:

Geometry exists: vertices and triangles are non-empty.
Index bounds: all triangle indices are within [0, vertices.size()).
No degenerate data: no NaN or infinite values in vertex positions.
Array consistency: if optional arrays (colors, face_colors, normals, uvs) are present, they must have the expected size (one element per vertex or per face, as appropriate).

Why would I call this?: After constructing a mesh manually, or after loading one from a file, call is_valid() to catch errors before rendering. A mesh that fails validation will either produce garbage output or crash the renderer.

Example: Mesh m = scimesh::obj_io::read_obj("model.obj");

if (!m.is_valid()) {

std::cerr << "Mesh failed validation — check your file!\n";

return;

}

// safe to render now

Returns: true if the mesh passes all checks.

See also: empty(), compute_bounding_box()

Definition at line 292 of file mesh.h.

◆ update_transparency()

void scimesh::Mesh::update_transparency ( )

inline

Recompute has_transparency from the mesh's colors.

Sets the flag when has_alpha() reports translucent colors. It never clears the flag, so a manually requested blend pass survives.

See also: is_transparent(), has_alpha()

Definition at line 256 of file mesh.h.

Member Data Documentation

◆ colors

std::vector<Color> scimesh::Mesh::colors

Per-vertex RGBA colors.

If non-empty, must have exactly vertices.size() elements. Used for vertex-colored rendering (interpolated across triangles).

See also: Color, has_colors(), face_colors

Definition at line 107 of file mesh.h.

◆ default_color

Color scimesh::Mesh::default_color = DEFAULT_COLOR

Fallback color when no per-vertex or per-face color is set.

Defaults to DEFAULT_COLOR (neutral light gray). You can change this to give a mesh a uniform color without populating colors.

See also: DEFAULT_COLOR

Definition at line 174 of file mesh.h.

◆ face_colors

std::vector<Color> scimesh::Mesh::face_colors

Per-face RGBA colors.

If non-empty, must have exactly triangles.size() elements. Overrides per-vertex colors when present (flat shading by face).

See also: Color, has_face_colors(), colors

Definition at line 115 of file mesh.h.

◆ has_transparency

bool scimesh::Mesh::has_transparency = false

Whether the mesh contains any transparent fragments.

You normally do not have to set this yourself: is_transparent() inspects default_color, colors and face_colors and is what the renderer uses, so a mesh whose colors have alpha < 1.0 renders translucent automatically (as do meshes loaded with such colors). Setting this to true forces the alpha-blending pass for a mesh that is not detected automatically (e.g. one whose transparency comes from an RGBA texture: the texture alpha is applied per fragment).

See also: is_transparent(), update_transparency(), colors, face_colors

Definition at line 187 of file mesh.h.

◆ normals

std::vector<Vec3> scimesh::Mesh::normals

Per-vertex surface normals (unit-length direction vectors).

If non-empty, must have exactly vertices.size() elements. Normals are used for lighting calculations (Blinn-Phong shading).

You can compute normals automatically with compute_vertex_normals().

See also: Vec3, has_normals(), compute_vertex_normals()

Definition at line 125 of file mesh.h.

◆ texture

Image scimesh::Mesh::texture

An optional texture image mapped via UV coordinates.

When set (width > 0), the rasterizer samples this image using the mesh's UV coordinates to color each pixel.

See also: Image, uvs, has_texture()

Definition at line 161 of file mesh.h.

◆ triangles

std::vector<Triangle> scimesh::Mesh::triangles

Triangle index triplets.

Each element {v0, v1, v2} points into vertices[]. A valid mesh must have at least one triangle.

See also: Triangle, vertices

Definition at line 94 of file mesh.h.

◆ uvs

std::vector<Vec2> scimesh::Mesh::uvs

Per-vertex texture coordinates (UVs).

If non-empty, must have exactly vertices.size() elements.

UVs are image-space coordinates, following the same rule as every other coordinate in scimesh: u = 0 is the left edge of the texture image and v = 0 its top edge, so (0, 0) addresses the top-left pixel of the texture and (1, 1) the bottom-right one. That is exactly what Image::sample_bilinear() expects, so the renderer passes the UVs through unchanged.

Note that OBJ and PLY files, OpenGL, rgl and tools like Blender and MeshLab store UVs with the opposite convention (v = 0 at the bottom), so those coordinates have to be converted once after loading — either by calling flip_uvs() or by subtracting from 1 while copying them (as examples/cpp/spot_cow/ does).

Only used when a texture image is also set; the renderer samples it with bilinear interpolation and multiplies it with the vertex color.

See also: Vec2, has_uvs(), texture, flip_uvs(), Image::sample_bilinear()

Definition at line 148 of file mesh.h.

◆ vertices

std::vector<Vec3> scimesh::Mesh::vertices

3D vertex positions.

Every mesh must have vertices. Each element is a Vec3 (x, y, z). Triangles reference these by index.

See also: Triangle, Vec3

Definition at line 86 of file mesh.h.

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

src/core/scimesh/mesh.h

Public Member Functions

Public Attributes

Detailed Description

Overview

Construction

Validation

Member Function Documentation

◆ compute_bounding_box()

◆ empty()

◆ has_alpha()

◆ has_colors()

◆ has_face_colors()

◆ has_normals()

◆ has_texture()

◆ has_uvs()

◆ is_transparent()

◆ is_valid()

◆ update_transparency()

Member Data Documentation

◆ colors

◆ default_color

◆ face_colors

◆ has_transparency

◆ normals

◆ texture

◆ triangles

◆ uvs

◆ vertices