---
title: "Light Omni"
canonical: "https://documentation.chaos.com/space/APPSDK/132781182/Light%20Omni"
format: markdown
---
In this chapter we'll cover the simplest light source in V-Ray - omni light. The omni light represents a point light source. It has parameters for the rate of decay and casting soft shadows (shadowRadius below).
## **Specific parameters**
---
Along with the common light parameters, the omni light has some that are specific for it:
- **areaSpeculars **- If true, the hilights will match the shape of the light; if false, hilights will always be calculated as from a point light
- **shadowRadius** - The size of the light; 0.0 is a point light, larger values produces soft (area) shadows
- **shadowRadius_tex** - A float texture that if present will override the shadows radius parameter
- **shadowSubdivs** - Controls the number of samples used to compute lighting
- **decay** - Exponent for the distance decay function. The default is the inverse square law. 0 disables decay.
> ℹ️ For the full list of parameters, please refer to the **LightOmni **plugin description in [API Reference Guides](https://docs-chaos.atlassian.net/wiki/spaces/APPSDK/pages/132644997).
## **Example**
---
The following example illustrates the use of the *LightOmni* with area shadows.
Python
```python
# Compatibility with Python 2.7.
from __future__ import print_function
# The directory containing the vray shared object should be present in the PYTHONPATH environment variable.
# Try to import the vray module from VRAY_SDK/python, if it is not in PYTHONPATH
import sys, os
VRAY_SDK = os.environ.get('VRAY_SDK')
if VRAY_SDK:
sys.path.append(os.path.join(VRAY_SDK, 'python'))
import vray
SCENE_PATH = os.path.join(os.environ.get('VRAY_SDK'), 'scenes')
# Change process working directory to SCENE_PATH in order to be able to load relative scene resources.
os.chdir(SCENE_PATH)
# The renderer is automatically closed after the `with` block.
with vray.VRayRenderer() as renderer:
# Register a simple log callback. Always useful for debugging.
def dumpMsg(renderer, message, level, instant):
if level == vray.LOGLEVEL_ERROR:
print("[ERROR]", message)
elif level == vray.LOGLEVEL_WARNING:
print("[Warning]", message)
elif level == vray.LOGLEVEL_INFO:
print("[info]", message)
# Uncomment for testing, but you might want to ignore these in real code
#else: print("[debug]", message)
renderer.setOnLogMessage(dumpMsg)
# Load scene from a file.
renderer.load(os.path.join(SCENE_PATH, 'lighting.vrscene'))
# Remove original light source from the scene.
del renderer.plugins["VRayLightDomeShape1"]
# LightOmni is a light source plugin that can be used to create physically accurate
# omnidirectional lights that cast rays in all directions from a single source.
light = renderer.classes.LightOmni()
# Specify the light position, rotation and scale.
light.transform = vray.Transform(
vray.Matrix(
vray.Vector(1.0, 0, 0),
vray.Vector(0, 1.0, 0),
vray.Vector(0, 0, 1.0)),
vray.Vector(0, 100.7851212422053, 48.17329059810792))
# Specify the light intensity based on the 'units' parameter.
light.intensity = 44000
# Specify the size of the light for shadows. The light is not directly visible to the camera.
# This parameter controls the softness of the shadows. A value of 0.0 produces a point light. Larger values result in soft (area) shadows.
light.shadowRadius = 1.2
# Specify shadow offset from the surface. Helps to prevent polygonal shadow artifacts on low-poly surfaces.
light.shadowBias = 0.02
# Specify a threshold for the light intensity, below which the light will
# not be computed. This can be useful in scenes with many lights, where you
# want to limit the effect of the lights to some distance around them.
# Larger values cut away more from the light; lower values make the light
# range larger. If you specify 0.0, the light will be calculated for all surfaces.
light.cutoffThreshold = 0.005
# Specify that the bumped normal should be used to check if the light direction is below the surface.
light.bumped_below_surface_check = True
# Start rendering.
renderer.startSync()
# Wait for rendering to end.
renderer.waitForRenderEnd()
```
C++
```c++
#define VRAY_RUNTIME_LOAD_PRIMARY
#include "vraysdk.hpp"
#include "vrayplugins.hpp"
#include "utils.h"
using namespace VRay;
using namespace VRay::Plugins;
using namespace std;
const char *BASE_PATH = getenv("VRAY_SDK");
string SCENE_PATH = (BASE_PATH ? string(BASE_PATH) : string(".")) + PATH_DELIMITER + "scenes";
int main() {
// Change process working directory to SCENE_PATH in order to be able to load relative scene resources.
changeCurrentDir(SCENE_PATH.c_str());
// Load V-Ray SDK library.
VRayInit init(NULL, true);
// Create an instance of VRayRenderer with default options.
// The renderer is automatically closed at the end of the current scope.
VRayRenderer renderer;
// It's recommended to always have a console log
renderer.setOnLogMessage(logMessage);
// Load scene from a file.
renderer.load("lighting.vrscene");
// Remove original light source from the scene.
renderer.deletePlugin("VRayLightDomeShape1");
// LightOmni is a light source plugin that can be used to create physically accurate
// omnidirectional lights that cast rays in all directions from a single source.
LightOmni light = renderer.newPlugin();
// Specify the light position, rotation and scale.
light.set_transform(Transform(
Matrix(
Vector(1.0, 0.0, 0.0),
Vector(0.0, 1.0, 0.0),
Vector(0.0, 0.0, 1.0)),
Vector(0.0, 100.7851212422053, 48.17329059810792)));
// Specify the light intensity based on the 'units' parameter.
light.set_intensity(44000);
// Specify the size of the light for shadows. The light is not directly visible to the camera.
// This parameter controls the softness of the shadows. A value of 0.0 produces a point light. Larger values result in soft (area) shadows.
light.set_shadowRadius(1.2f);
// Specify shadow offset from the surface. Helps to prevent polygonal shadow artifacts on low-poly surfaces.
light.set_shadowBias(0.02f);
// Specify a threshold for the light intensity, below which the light will
// not be computed. This can be useful in scenes with many lights, where you
// want to limit the effect of the lights to some distance around them.
// Larger values cut away more from the light; lower values make the light
// range larger. If you specify 0.0, the light will be calculated for all surfaces.
light.set_cutoffThreshold(0.005f);
// Specify that the bumped normal should be used to check if the light direction is below the surface.
light.set_bumped_below_surface_check(true);
// Start rendering.
renderer.startSync();
// Wait for rendering to end.
renderer.waitForRenderEnd();
return 0;
}
```
C#.NET
```csharp
using System;
using System.IO;
using VRay;
using VRay.Plugins;
namespace _02_omni
{
class Program
{
static void Main(string[] args)
{
string SCENE_PATH = Path.Combine(Environment.GetEnvironmentVariable("VRAY_SDK"), "scenes");
// Change process working directory to SCENE_PATH in order to be able to
// load relative scene resources.
Directory.SetCurrentDirectory(SCENE_PATH);
// Create an instance of VRayRenderer with default options. The renderer is automatically closed after the `using` block.
using (VRayRenderer renderer = new VRayRenderer())
{
// Add a listener for any type of log message.
renderer.LogMessage += new EventHandler((source, e) =>
{
// You can remove the if for testing, but you might want to ignore Debug in real code
if (e.LogLevel != LogLevelType.Debug)
{
Console.WriteLine(String.Format("[{0}] {1}", e.LogLevel.ToString(), e.Message));
}
});
// Load scene from a file.
renderer.Load("lighting.vrscene");
// Remove original light source from the scene.
renderer.DeletePlugin("VRayLightDomeShape1");
// LightOmni is a light source plugin that can be used to create physically accurate
// omnidirectional lights that cast rays in all directions from a single source.
LightOmni light = renderer.NewPlugin();
// Specify the light position, rotation and scale.
light.Transform = new Transform(
new Matrix(
new Vector(1.0, 0, 0),
new Vector(0, 1.0, 0),
new Vector(0, 0, 1.0)),
new Vector(0, 100.7851212422053, 48.17329059810792));
// Specify the light intensity based on the 'units' parameter.
light.Intensity = 44000;
// Specify the size of the light for shadows. The light is not directly visible to the camera.
// This parameter controls the softness of the shadows. A value of 0.0 produces a point light. Larger values result in soft (area) shadows.
light.ShadowRadius = 1.2F;
// Specify shadow offset from the surface. Helps to prevent polygonal shadow artifacts on low-poly surfaces.
light.ShadowBias = 0.02F;
// Specify a threshold for the light intensity, below which the light will
// not be computed. This can be useful in scenes with many lights, where you
// want to limit the effect of the lights to some distance around them.
// Larger values cut away more from the light; lower values make the light
// range larger. If you specify 0.0, the light will be calculated for all surfaces.
light.CutoffThreshold = 0.005F;
// Specify that the bumped normal should be used to check if the light direction is below the surface.
light.BumpedBelowSurfaceCheck = true;
// Start rendering.
renderer.StartSync();
// Wait for rendering to end.
renderer.WaitForRenderEnd();
}
}
}
}
```
Node.js
```javascript
var path = require('path');
var vray = require(path.join(process.env.VRAY_SDK, 'node', 'vray'));
var SCENE_PATH = path.join(process.env.VRAY_SDK, 'scenes');
// Change process working directory to SCENE_PATH in order to be able to load relative scene resources.
process.chdir(SCENE_PATH);
// Create an instance of VRayRenderer with default options.
var renderer = vray.VRayRenderer();
// It's recommended to always have a console log callback
renderer.on("logMessage", function(message, level, instant) {
if (level == vray.LOGLEVEL_ERROR)
console.log("[ERROR] ", message);
else if (level == vray.LOGLEVEL_WARNING)
console.log("[Warning] ", message);
else if (level == vray.LOGLEVEL_INFO)
console.log("[info] ", message);
// Uncomment for testing, but you might want to ignore these in real code
//else console.log("[debug] ", message);
});
// Load scene from a file asynchronously.
renderer.load("lighting.vrscene", function(err) {
if (err) throw err;
// Remove original light source from the scene.
delete renderer.plugins["VRayLightDomeShape1"];
// LightOmni is a light source plugin that can be used to create physically accurate
// omnidirectional lights that cast rays in all directions from a single source.
var light = renderer.classes.LightOmni();
// Specify the light position, rotation and scale.
light.transform = vray.Transform(
vray.Matrix(
vray.Vector(1.0, 0, 0),
vray.Vector(0, 1.0, 0),
vray.Vector(0, 0, 1.0)),
vray.Vector(0, 100.7851212422053, 48.17329059810792));
// Specify the light intensity based on the 'units' parameter.
light.intensity = 44000;
// Specify the size of the light for shadows. The light is not directly visible to the camera.
// This parameter controls the softness of the shadows. A value of 0.0 produces a point light. Larger values result in soft (area) shadows.
light.shadowRadius = 1.2;
// Specify shadow offset from the surface. Helps to prevent polygonal shadow artifacts on low-poly surfaces.
light.shadowBias = 0.02;
// Specify a threshold for the light intensity, below which the light will
// not be computed. This can be useful in scenes with many lights, where you
// want to limit the effect of the lights to some distance around them.
// Larger values cut away more from the light; lower values make the light
// range larger. If you specify 0.0, the light will be calculated for all surfaces.
light.cutoffThreshold = 0.005;
// Specify that the bumped normal should be used to check if the light direction is below the surface.
light.bumped_below_surface_check = true;
// Start rendering.
renderer.start(function(err) {
if (err) throw err;
// Wait for rendering to end.
renderer.waitForRenderEnd(function() {
renderer.close();
});
});
});
```
## **Result**
---
** **
The scene used for this render is called "Lighting_Omni.vrscene" and can be found in the [scene bundle](https://drive.google.com/file/d/1Wdp9M2AO-YcoPbBwiF0MAPKsDm5AxVqw/view?usp=sharing)[ ](https://drive.google.com/file/d/1Wdp9M2AO-YcoPbBwiF0MAPKsDm5AxVqw/view?usp=sharing)(comments on the different parameters available inside).