IBL

IBL is a method of lighting objects using images from the surrounding environment as light sources. It provides realistic reflection and global illumination effects that are difficult to express with simple light sources alone, maximizing the realism of 3D scenes.

1. Core Components of IBL

RedGPU's Image-Based Lighting (IBL) system analyzes HDR environment maps or cubemap images to automatically create the following three core resources.

1.1 Irradiance Texture

Acts as the basic shading and ambient light for objects, giving natural color even where there is no direct light source.

1.2 IBL Texture (Specular Texture)

Responsible for the effect of the surrounding environment being reflected on the object surface. Expresses reflections from surfaces like metal or glass in Physically Based Rendering (PBR) materials.

1.3 Environment Texture

Data that maintains the original image as a high-resolution cubemap, mainly used as a background texture for SkyBox.

2. Implementation: Creation and Application

To apply IBL, you must create the resource and then register it in the camera view (View3D).

// 1. Create IBL resource (HDR file recommended)
const ibl = new RedGPU.Resource.IBL(
    redGPUContext, 
    'https://redcamel.github.io/RedGPU/examples/assets/hdr/2k/the_sky_is_on_fire_2k.hdr'
);

// 2. Apply IBL to View (Lighting effect)
view.ibl = ibl;

// 3. Apply SkyBox to View (Visual background)
view.skybox = new RedGPU.Display.SkyBox(redGPUContext, ibl.environmentTexture);

3. Live Example: Environmental Setup

The example below shows the result of simultaneously creating IBL and Skybox from an HDR source. Right now it just looks like a 360-degree background, but this space is already filled with physically accurate light data.

4. True Value: Synergy with GLTF

Simply looking at the background (Skybox) may not seem to make much difference. But the true value of this environmental setup is revealed when loading GLTF models, which will be covered in the next chapter.

Detailed models created externally mostly use PBR (Physically Based Rendering) materials. IBL provides these models with realistic reflection data and soft environment light, allowing the models to implement photorealistic textures as if they were actually present in that space.

Next Steps

Based on the objects and environment settings learned so far, let's learn more deeply how to load and control models in actual projects.

• GLTF Loader