©Anton Podvalny

Table of Contents

In this chapter we'll cover another area light - mesh light. It can turn a geometry plugin into a light source and can be textured.

Parameters


Along with the common light parameters, the LightMesh plugin has the following specific ones:

  • noDecay - If set to true, light intensity will not fall off with distance. By default the inverse square law applies.
  • doubleSided - Whether to emit light from the back sides of the triangles.
  • geometry - A geometry plugin that will define the shape of the light. Note that complex geometries may make mesh lights slower and noisier.
  • tex - A texture plugin to map onto the geometry for light color. This requires that the geometry plugin has valid UV data.
  • use_tex - You also have to set this to true to actually use the tex parameter.
  • tex_resolution - The texture is actually resampled at this resolution. The default is 256, so even if you have a high resolution image, it may look pixelated if you don't increase this. This will consume more memory.

 

Example


Here's an example how to assign a geometry to a MeshLight:

# 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"]
    geometry = renderer.plugins['SphereAShape@mesh12']
    # LightMesh is a light source plugin that can be used to create lights that take their shapes and sizes from a mesh object.
    light = renderer.classes.LightMesh()
    # Specify the geometry that will be used for light emission.
    light.geometry = geometry
    # Specify the light intensity based on the 'units' parameter.
    light.intensity = 80
    # Specify the color of the light in RGB float values and alpha(1.0f)
    light.color = vray.AColor(0.628, 1, 0.8283096)
    # Specify the light position, rotation and scale.
    light.transform = vray.Transform(
        vray.Matrix(
            vray.Vector(1, 0, 0),
            vray.Vector(0, 1, 0),
            vray.Vector(0, 0, 1)),
        vray.Vector(0, 0, 0))
    # Specify shadow offset from the surface. Helps to prevent polygonal shadow artifacts on low-poly surfaces.
    light.shadowBias = 0.02
    # 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()
#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");
	Plugin geometry = renderer.getPlugin("SphereAShape@mesh12");
	// LightMesh is a light source plugin that can be used to create lights that take their shapes and sizes from a mesh object.
	LightMesh light = renderer.newPlugin<LightMesh>();
	// Specify the geometry that will be used for light emission.
	light.set_geometry(geometry);
	// Specify the light intensity based on the 'units' parameter.
	light.set_intensity(80);
	// Specify the color of the light in RGB float values and alpha(1.0f)
	light.set_color(AColor(0.628, 1, 0.8283096));
	// 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, 0.0, 0.0)));
	// Specify shadow offset from the surface. Helps to prevent polygonal shadow artifacts on low-poly surfaces.
	light.set_shadowBias(0.02f);
	// 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;
}
using System;
using System.IO;
using VRay;
using VRay.Plugins;

namespace _03_geometric
{
    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<MessageEventArgs>((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");
                Plugin geometry = renderer.GetPlugin("SphereAShape@mesh12");
                // LightMesh is a light source plugin that can be used to create lights that take their shapes and sizes from a mesh object.
                LightMesh light = renderer.NewPlugin<LightMesh>();
                // Specify the geometry that will be used for light emission.
                light.Geometry = geometry;
                // Specify the light intensity based on the 'units' parameter.
                light.Intensity = 80;
                // Specify the color of the light in RGB float values and alpha = 1.
                light.Color = new AColor(0.628, 1, 0.8283096);
                // Specify the light position, rotation and scale.
                light.Transform = new Transform(
                    new Matrix(
                        new Vector(1, 0, 0),
                        new Vector(0, 1, 0),
                        new Vector(0, 0, 1)),
                    new Vector(0, 0, 0));
                // Specify shadow offset from the surface. Helps to prevent polygonal shadow artifacts on low-poly surfaces.
                light.ShadowBias = 0.02F;
                // Specify that the bumped normal should be used to check if the light direction is below the surface.
                light.BumpedBelowSurfaceCheck = true;
                // Specify the number of parameter samples for motion blur.
                light.Nsamples = 1;
                // Start rendering.
                renderer.StartSync();
                // Wait for rendering to end.
                renderer.WaitForRenderEnd();
            }
        }
    }
}
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"];
    var geometry = renderer.plugins["SphereAShape@mesh12"];
    // LightMesh is a light source plugin that can be used to create lights that take their shapes and sizes from a mesh object.
    var light = renderer.classes.LightMesh();
    // Specify the geometry that will be used for light emission.
    light.geometry = geometry;
    // Specify the light intensity based on the 'units' parameter.
    light.intensity = 80;
    // Specify the color of the light in RGB float values and alpha(1.0f)
    light.color = vray.AColor(0.628, 1, 0.8283096);
    // Specify the light position, rotation and scale.
    light.transform = vray.Transform(
        vray.Matrix(
            vray.Vector(1, 0, 0),
            vray.Vector(0, 1, 0),
            vray.Vector(0, 0, 1)),
        vray.Vector(0, 0, 0));
    // Specify shadow offset from the surface. Helps to prevent polygonal shadow artifacts on low-poly surfaces.
    light.shadowBias = 0.02;
    // 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_Mesh.vrscene" and can be found in the scene bundle (comments to the different parameters available inside).

  • No labels