> For the complete documentation index, see [llms.txt](https://bnpr.gitbook.io/bnpr/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bnpr.gitbook.io/bnpr/shaders/basic-matcap.md).

# Basic Matcap

This is the most basic matcap projection. Its a representation of normals relative to the camera. For a Sphere the matcap projection is basically just screen space that tracks with the object (can be useful in other contexts too).

![](/files/-MlP0u9e_67_wSmrzVrL)

If you want to use an image texture as your matcap, you first need to remap from (-1 : 1) to (0 : 1) like this.

![](/files/-MlP11ZfYez9IRMTqwc3)

On a sphere, the texture will look undistorted you can make a bad Fresnel effect with matcap mapping.

![](/files/-MlP1EZQkN6IpXzihF1X)

Or you can create crispy procedural matcaps to make for example NPR metal shaders or like in this case create a "mask" to mix in lighting, color and stepped gradient effects.

![](/files/-MlP1OJsL5x2EYaOeRHr)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://bnpr.gitbook.io/bnpr/shaders/basic-matcap.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.
