Skip to main content

​
Overview

Atlas provides a comprehensive lighting system with support for ambient, directional, point, spot, and area lights. All light types support shadow mapping and are optimized for GPU rendering with aligned buffer structures.

​
Light Types

​
AmbientLight

Ambient light provides uniform illumination across the entire scene.
​
color
Color
The color of the ambient light reflected into all objects.
​
intensity
float
The intensity with which the ambient light is applied.

​
DirectionalLight

Directional lights simulate distant light sources like the sun, with parallel rays.

​
Constructor

​
DirectionalLight
constructor
Creates a new directional light.Parameters:
  • dir - Direction vector (will be normalized) (default: {0.0f, -1.0f, 0.0f})
  • color - Light color (default: Color::white())
  • shineColor - Specular highlight color (default: Color::white())
  • intensity - Light intensity (default: 1.0f)

​
Properties

​
direction
Magnitude3d
Direction in which the light is pointing (normalized vector).
​
color
Color
default:"Color::white()"
The color of the light.
​
shineColor
Color
default:"Color::white()"
The color used for specular highlights.
​
intensity
float
default:"1.0f"
The light intensity multiplier.
​
shadowRenderTarget
RenderTarget*
Render target that holds the shadow map (when shadows are enabled).

​
Methods

​
setColor
void
Sets the light color.Parameters:
  • color - New color for the light
​
castShadows
void
Enables shadow casting for this light.Parameters:
  • window - The window in which to cast shadows
  • resolution - Shadow map resolution (default: 4096)

​
Light (Point Light)

Point lights emit light in all directions from a single point, with distance-based attenuation.

​
Constructor

​
Light
constructor
Creates a new point light.Parameters:
  • pos - Position in 3D space (default: {0.0f, 0.0f, 0.0f})
  • color - Light color (default: Color::white())
  • distance - Distance the light reaches (default: 50.0f)
  • shineColor - Specular highlight color (default: Color::white())
  • intensity - Light intensity (default: 1.0f)

​
Properties

​
position
Position3d
default:"{0.0f, 0.0f, 0.0f}"
Position of the light in 3D space.
​
color
Color
default:"Color::white()"
The color of the light.
​
shineColor
Color
default:"Color::white()"
The color used for specular highlights.
​
intensity
float
default:"1.0f"
Light intensity multiplier.
​
distance
float
default:"50.0f"
Distance to which the light reaches.
​
shadowRenderTarget
RenderTarget*
Render target that holds the shadow cubemap.
​
debugObject
shared_ptr<CoreObject>
Debug object for visualizing the light in the scene.

​
Methods

​
setColor
void
Sets the light color.Parameters:
  • newColor - New color for the light
​
calculateConstants
PointLightConstants
Calculates attenuation constants for the point light.Returns: Structure containing distance, constant, linear, quadratic, and radius values
​
castShadows
void
Enables shadow casting for this light.Parameters:
  • window - The window in which to cast shadows
  • resolution - Shadow map resolution (default: 2048)
​
createDebugObject
void
Creates a debug object to visualize the light in the scene.
​
addDebugObject
void
Adds the debug object to the window.Parameters:
  • window - The window to add the debug object to

​
Spotlight

Spotlights emit light in a cone from a specific position and direction.

​
Constructor

​
Spotlight
constructor
Creates a new spotlight.Parameters:
  • pos - Position in 3D space (default: {0.0f, 0.0f, 0.0f})
  • dir - Direction vector (default: {0.0f, -1.0f, 0.0f})
  • color - Light color (default: Color::white())
  • angle - Inner cone angle in degrees (default: 35.0f)
  • outerAngle - Outer cone angle in degrees (default: 40.0f)
  • shineColor - Specular highlight color (default: Color::white())
  • intensity - Light intensity (default: 1.0f)
  • range - Light range (default: 50.0f)

​
Properties

​
position
Position3d
default:"{0.0f, 0.0f, 0.0f}"
Position of the spotlight in 3D space.
​
direction
Magnitude3d
default:"{0.0f, -1.0f, 0.0f}"
Direction in which the spotlight is pointing.
​
color
Color
default:"Color::white()"
The color of the spotlight.
​
shineColor
Color
default:"Color::white()"
The color used for specular highlights.
​
intensity
float
default:"1.0f"
Light intensity multiplier.
​
range
float
default:"50.0f"
Maximum range of the spotlight.
​
cutOff
float
Inner cone angle of the spotlight (cosine of angle in radians).
​
outerCutoff
float
Outer cone angle of the spotlight (cosine of angle in radians).
​
shadowRenderTarget
RenderTarget*
Render target for shadow mapping.
​
debugObject
shared_ptr<CoreObject>
Debug object for visualizing the spotlight.

​
Methods

​
setColor
void
Sets the spotlight color.Parameters:
  • newColor - New color for the spotlight
​
lookAt
void
Makes the spotlight look at a target position.Parameters:
  • target - Position to look at
​
castShadows
void
Enables shadow casting.Parameters:
  • window - The window in which to cast shadows
  • resolution - Shadow map resolution (default: 2048)
​
createDebugObject
void
Creates a debug object to visualize the spotlight.
​
addDebugObject
void
Adds the debug object to the window.Parameters:
  • window - The window to add the debug object to
​
updateDebugObjectRotation
void
Updates the rotation of the debug object to match the spotlight direction.

​
AreaLight

Area lights are rectangular light sources with controllable emission angle and two-sided emission.

​
Properties

​
position
Position3d
default:"{0.0, 0.0, 0.0}"
Center position of the rectangular light.
​
right
Magnitude3d
default:"{1.0, 0.0, 0.0}"
Oriented axis for width direction (normalized).
​
up
Magnitude3d
default:"{0.0, 1.0, 0.0}"
Oriented axis for height direction (normalized).
​
size
Size2d
default:"{1.0, 1.0}"
Width and height of the rectangle.
​
color
Color
default:"Color::white()"
Diffuse/emissive color of the light.
​
shineColor
Color
default:"Color::white()"
Specular highlight color.
​
intensity
float
default:"1.0f"
Light intensity multiplier.
​
range
float
default:"50.0f"
Maximum range of the light.
​
angle
float
default:"90.0f"
Emission cone half-angle in degrees around the plane normal (90 = hemisphere).
​
castsBothSides
bool
default:"false"
If true, the light emits on both sides of the rectangle plane.
​
rotation
Rotation3d
default:"{0.0, 0.0, 0.0}"
Rotation tracking for the area light in degrees.
​
debugObject
shared_ptr<CoreObject>
Optional debug object for visualizing the area light.
​
shadowRenderTarget
RenderTarget*
Render target for shadow mapping.

​
Methods

​
getNormal
Magnitude3d
Computes the plane normal (normalize(cross(right, up))).Returns: Normalized normal vector
​
setColor
void
Sets the diffuse color.Parameters:
  • c - New color
​
setRotation
void
Sets absolute rotation and updates right/up axes accordingly.Parameters:
  • r - Rotation in degrees (roll Z, pitch X, yaw Y)
​
rotate
void
Applies a delta rotation and updates right/up axes.Parameters:
  • delta - Delta rotation in degrees
​
createDebugObject
void
Creates a debug object to visualize the area light rectangle.
​
addDebugObject
void
Adds the debug object to the window.Parameters:
  • window - The window to add the debug object to
​
castShadows
void
Enables shadow casting.Parameters:
  • window - The window in which to cast shadows
  • resolution - Shadow map resolution (default: 2048)

​
GPU Buffer Structures

Atlas provides GPU-aligned structures for efficient light data transfer:
  • GPUDirectionalLight - Matches GLSL DirectionalLight struct
  • GPUPointLight - Matches GLSL PointLight struct
  • GPUSpotLight - Matches GLSL SpotLight struct
  • GPUAreaLight - Matches GLSL AreaLight struct
  • GPUShadowParams - Matches GLSL ShadowParameters struct
These structures use alignas(16) to ensure proper GPU memory alignment.

​
Example Usage

// Create a directional light (sun)
DirectionalLight dirLight({0.0f, -1.0f, 0.0f}, Color::white());
dirLight.setColor(Color(1.0f, 0.95f, 0.8f));
dirLight.castShadows(window);
scene.addDirectionalLight(&dirLight);

// Create a point light
Light pointLight({10.0f, 10.0f, 10.0f}, Color::white(), 50.0f);
pointLight.setColor(Color(1.0f, 0.9f, 0.7f));
pointLight.castShadows(window);
pointLight.createDebugObject();
pointLight.addDebugObject(window);
scene.addPointLight(&pointLight);

// Create a spotlight
Spotlight spotLight({0.0f, 10.0f, 0.0f}, {0.0f, -1.0f, 0.0f}, Color::white(), 30.0f, 35.0f);
spotLight.setColor(Color(0.7f, 0.8f, 1.0f));
spotLight.castShadows(window);
spotLight.lookAt({0.0f, 0.0f, 0.0f});
spotLight.createDebugObject();
spotLight.addDebugObject(window);
scene.addSpotlight(&spotLight);

// Create an area light
AreaLight areaLight;
areaLight.position = {0.0, 5.0, 0.0};
areaLight.size = {2.0, 2.0};
areaLight.setRotation({0.0, 45.0, 0.0});
areaLight.color = Color::white();
areaLight.intensity = 2.0f;
areaLight.castsBothSides = true;
areaLight.createDebugObject();
areaLight.addDebugObject(window);

Build docs developers (and LLMs) love

Get started for freeTalk to us