Reflections

What “reflection” means in rendering

In everyday language, a reflection is a mirror like image, for example a floor that shows the stage lights, or a glossy surface that shows nearby objects.

In physics, the word is broader, light hits a surface and some of it is sent back into the world. In that sense, almost everything you see is already “reflected light”, because you can only see an object if light leaves it and reaches your eye or the camera.

What most users mean by “I want reflections” is a very specific case:

• Specular reflection, the mirror like part of shading

• Often including secondary light transport, meaning light that has already bounced off something else

A simple bounce model

To understand why reflections do not appear automatically, it helps to think in “bounces”:

1. Direct lighting (first interaction) Light goes from a light source to a surface and then to the camera.

2. Second bounce and beyond (indirect transport) Light hits one surface, reflects, then hits another surface, reflects again, and so on. Mirror like reflections of other objects, colored light bleeding, and many glossy effects are part of these additional bounces.

Accurately computing many bounces in real time is expensive.

Why real time rendering does not automatically show mirror reflections

Depence is designed for real time performance. Its renderer is based on rasterization. You do not need to know the term, the practical consequence is:

• The image is computed primarily from what is visible in the current camera view

• The renderer does not automatically trace rays into the scene to find what a pixel would hit after bouncing

• Geometry that is behind the camera, or outside the screen, is not automatically known for reflections

So if a material becomes very smooth and very reflective, it needs a clear answer to the question: “What environment should this pixel reflect?”

If no reflection source is configured, the renderer has little or nothing to sample, the result can look like missing reflections, dark surfaces, or only the direct highlight from lights.

Material controls and what they really do

Roughness

• High roughness spreads the specular reflection, it becomes blurry and weak

• Low roughness concentrates the specular reflection, it becomes sharp and mirror like This is the case where users most notice missing reflection information

Metalness

Metalness changes how much of the surface response is “dielectric” (plastic, paint, wood) vs “metal”.

• Dielectrics usually show a combination of diffuse plus specular

• Metals strongly reduce diffuse response and rely heavily on specular reflection

Important point: Increasing metalness or decreasing roughness does not create reflection content. It only increases the need for a reflection source.

👉 Here you can read more about setting up your material

How reflections are provided in Depence

Depence offers explicit, controllable reflection methods. These are the reflection “sources” that define what a surface can reflect.

1) Planar Reflections

Best for:

• floors, water surfaces, mirrors that are flat

What it does:

• Produces an accurate mirror result for one plane, because it can render a mirrored view for that plane

Typical limitation:

• It is tied to a plane, it is not a general solution for every curved or complex surface

👉 Here you can find out how to create a Planar-Reflector

2) Reflection Probe (one global probe)

Best for:

• general environment reflections across the scene, especially for glossy materials

What it does:

• Provides an approximate “environment capture” that materials can reflect

Typical limitation:

• It is an approximation, and only one probe is supported, so it cannot perfectly match every room or area

3) Atmosphere HDRI, Environment Reflections

Best for:

• outdoor scenes, large environments, or any scene that needs a believable world to reflect

What it does:

• Uses an HDR image as an environment, materials can reflect this even if there is little surrounding geometry

Practical takeaway: If a scene is sparse, or the camera is in an open area, an HDRI often makes the biggest difference for believable reflections.