Philip Rideout
3ada971d8a
matdbg should use Flattener / Unflattener rather than imitating them, this is phase 1.
269 lines
11 KiB
Markdown
269 lines
11 KiB
Markdown
# matdbg
|
|
|
|
1. [Capabilities](#capabilities)
|
|
1. [Setup for Desktop](#setup-for-desktop)
|
|
1. [Setup for Android](#setup-for-android)
|
|
1. [Debugger Usage](#debugger-usage)
|
|
1. [Architecture Overview](#architecture-overview)
|
|
1. [C++ Server](#c-server)
|
|
1. [JavaScript Client](#javascript-client)
|
|
1. [HTTP Requests](#http-requests)
|
|
1. [WebSocket Messages](#websocket-messages)
|
|
1. [Wish List](#wish-list)
|
|
1. [Screenshot](#screenshot)
|
|
1. [Material Chunks](#material-chunks)
|
|
|
|
## Capabilities
|
|
|
|
matdbg is a library and web application that enables debugging and live-editing of Filament shaders.
|
|
At the time of this writing, the following capabilities are supported.
|
|
|
|
- OpenGL: Editing GLSL
|
|
- Metal: Editing MSL
|
|
- Vulkan: Editing transpiled GLSL, displaying disassembled SPIR-V
|
|
|
|
Note that a given material can be built with multiple backends, even though only one backend
|
|
is active in a particular session. For example, if the current app is using Vulkan, it is still
|
|
possible to inspect the Metal shaders, as long as the material has been built with Metal support
|
|
included.
|
|
|
|
## Setup for Desktop
|
|
|
|
When using the easy build script, include the `-d` argument. For example:
|
|
|
|
./build.sh -fd debug gltf_viewer
|
|
|
|
The `d` enables a CMake option called FILAMENT_ENABLE_MATDBG and the `f` ensures that CMake gets
|
|
re-run so that the option is honored.
|
|
|
|
Next, set an environment variable as follows. In Windows, use `set` instead of `export`.
|
|
|
|
export FILAMENT_MATDBG_PORT=8080
|
|
|
|
Next, launch any app that links against a debug build of a Filament and point your web browser to
|
|
http://localhost:8080. Skip ahead to **Debugger Usage**.
|
|
|
|
## Setup for Android
|
|
|
|
Rebuild Filament for Android after enabling a CMake option called FILAMENT_ENABLE_MATDBG. Note that
|
|
CMake is invoked from several places for Android (both gradle and our easy build script), so one
|
|
pragmatic and reliable way of doing this is to simply hack `CMakeLists.txt` and
|
|
`filament-android/CMakeLists.txt` by unconditionally setting FILAMENT_ENABLE_MATDBG to ON.
|
|
|
|
After rebuilding Filament with the option enabled, ensure that internet permissions are enabled in
|
|
your app by adding the following into your manifest as a child of the `<manifest>` element.
|
|
|
|
<uses-permission android:name="android.permission.INTERNET" />
|
|
|
|
Now launch your app as usual. The Filament Engine sets up a server that is hardcoded to listen to
|
|
port 8081. Next, you will need to forward your device's TCP port 8081 to your host port of choice.
|
|
For example, to forward the matdbg server on your device to port 8081 on your host machine, do the
|
|
following:
|
|
|
|
adb forward tcp:8081 tcp:8081
|
|
|
|
This lets you go to http://localhost:8081 in Chrome on your host machine.
|
|
|
|
Note that we generally use a release build of Filament when running on Android, so the shaders
|
|
are optimized and very unreadable. This can be avoided by modifying the build such that `-g` is
|
|
passed to matc even in release builds.
|
|
|
|
## Debugger Usage
|
|
|
|
After opening the matdbg page in your browser, the usual first step is to select a material in the
|
|
upper-left pane. Sometimes you might need force your app to redraw (e.g. by resizing the window) in
|
|
order make the materials selectable.
|
|
|
|
The next step is to select an active (boldface) shader variant in the lower-left pane. This allows
|
|
you to view the GLSL, MSL, and SPIR-V code that was generated by `matc` or `filamat`.
|
|
|
|
In the sidebar, inactive shader variants have a disabled appearance, but they can still be examined
|
|
in the shader editor. The active status of each shader program is refreshed every second.
|
|
|
|
You can also make modifications to GLSL or MSL, so long as the shader inputs and uniforms remain
|
|
intact. After making an edit, click the `[rebuild]` button in the header. Note that your edits will
|
|
be lost after closing the web page.
|
|
|
|
## Keyboard Shortcuts
|
|
|
|
To save an edit, press **Cmd+S** (**Ctrl+S** on Linux/Windows) as an alternative to clicking
|
|
`[rebuild]`.
|
|
|
|
If the editor has focus, you can navigate between materials by holding **Shift+Ctrl** while
|
|
pressing the up or down arrow. Navigation between variants is similar, just use left / right instead
|
|
of up / down.
|
|
|
|
## Architecture Overview
|
|
|
|
The matdbg library has two parts: a C++ server and a JavaScript client. The C++ server is
|
|
responsible for instancing a [civetweb][1] context that handles HTTP and WebSocket requests. The
|
|
JavaScript client is a small web app that contains a view into an in-browser database of materials.
|
|
|
|
The WebSocket server receives push-style notifications from the client (such as edits) while
|
|
the HTTP server responds to material queries using simple JSON messages.
|
|
|
|
When a new WebSocket connection is established, the client asks the server for a list of materials
|
|
in order to populate its in-browser database. If the connection is lost (e.g. if the app crashes),
|
|
then the database stays intact and the web app is still functional. If a new Filament app is
|
|
launched, the client inserts entries into its database rather than replacing the existing set.
|
|
|
|
The material database is cleared only when the web page is manually refreshed by the user.
|
|
|
|
## C++ Server
|
|
|
|
The civetweb server is wrapped by our `DebugServer` class, whose public interface is comprised of a
|
|
couple methods that are called from the Filament engine:
|
|
|
|
- **addMaterial** Notifies the debugger that the given material package is being loaded into the
|
|
engine.
|
|
- **setEditCallback** Sets up a callback that allows the Filament engine to listen for shader edits.
|
|
- **setQueryCallback** Sets up a callback that allows the debugger to ask for current information.
|
|
|
|
## JavaScript Client
|
|
|
|
The web app is written in simple, modern JavaScript and avoids frameworks like React or Angular. It
|
|
uses the following third-party libraries which are fetched from a CDN using `<script>`. This allows
|
|
us to avoid adding them to our git repo, and leads to good caching behavior.
|
|
|
|
- **mustache** Popular tiny library that converts template strings into HTML.
|
|
- **monaco** The engine behind Visual Studio Code.
|
|
- We've configured this for C++ for somewhat reasonable syntax highlighting.
|
|
- If desired we could extend the editor to better handle GLSL and SPIR-V.
|
|
|
|
All the source code for our web app is contained in a single file (`script.js`) and the mustache
|
|
template strings are specified using `<template>` tags in `index.html`.
|
|
|
|
The web app basically provides a view over a pseudo-database which is a just a global variable
|
|
that holds a dictionary that maps from material id's to objects that conform to the JSON described
|
|
below.
|
|
|
|
## HTTP requests
|
|
|
|
The server responds to the following GET requests by returning a JSON blob. The `{id}` in these
|
|
requests is a concept specific to matdbg (not Filament) which is an 8-digit hex string that hashes
|
|
the entire binary content of the material package.
|
|
|
|
---
|
|
|
|
`/api/matids`
|
|
|
|
Returns an array containing the id for each known material. Example:
|
|
|
|
```json
|
|
["e4c41141", "44ae2b62", "9dab8a03"]
|
|
```
|
|
|
|
---
|
|
|
|
`/api/materials`
|
|
|
|
Returns an array with all information (except shader source) for all known materials. Example:
|
|
|
|
```json
|
|
[{
|
|
"matid": "e4c41141",
|
|
"name": "uiBlit",
|
|
"version": 4,
|
|
"shading": { "model": "unlit", "vertex_domain": "object", ... },
|
|
"raster": { "blending": "transparent", "color_write": "true", ... },
|
|
"opengl": [
|
|
{ "index": " 0", "shaderModel": "gl41", "pipelineStage": "vertex ", "variantString": "", "variant": 0 },
|
|
{ "index": " 1", "shaderModel": "gl41", "pipelineStage": "fragment", "variantString": "", "variant": 0 },
|
|
],
|
|
"vulkan": [],
|
|
"metal": [],
|
|
"required_attributes": ["position", "color", "uv0"]
|
|
},
|
|
{
|
|
"matid": "44ae2b62",
|
|
...
|
|
}]
|
|
```
|
|
|
|
Some of the returned data may seem redundant (e.g. the `index` and `variantString` fields) but
|
|
these allow the client to be very simple by passing the raw JSON into [mustache][4] templates.
|
|
Moreover it helps prevent duplication of knowledge between C++ and JavaScript.
|
|
|
|
This format of this message is also used for the in-browser "database" of materials.
|
|
|
|
---
|
|
|
|
`/api/material?matid={id}`
|
|
|
|
Returns all information (except shader source) for a specific known material. The JSON response
|
|
is equivalent to one of the items in the top-level array in `/api/materials`.
|
|
|
|
---
|
|
|
|
`/api/active`
|
|
|
|
Returns an object that maps from material ids to their active shader variants. Example:
|
|
|
|
```json
|
|
{"b38d4ad0": ["opengl", 5] , "44ae2b62": ["opengl", 1, 4] }
|
|
```
|
|
|
|
Each numeric element in the list is a variant mask. For example, at the time of this writing,
|
|
Filament has 7-bit mask, so each number in the list is between 0 and 127.
|
|
|
|
---
|
|
|
|
`/api/shader?matid={id}&type=[glsl|spirv|msl]&[glindex|vkindex|metalindex]={index}`
|
|
|
|
Returns the entire shader code for the given variant. This is the only HTTP request that returns
|
|
text instead of JSON.
|
|
|
|
The `type` field in the request selects the desired shading language, not the backend. For example,
|
|
for Vulkan it can select between SPIR-V or decompiled GLSL. Note that the original GLSL that was
|
|
used to create the SPIR-V is not available.
|
|
|
|
---
|
|
|
|
## WebSocket messages
|
|
|
|
Unlike HTTP requests, WebSocket messages can be pushed at any time and can travel in either
|
|
direction. In our homegrown protocol, every WebSocket message starts with a command that matches
|
|
\[A-Z\_]+ followed by a space character. Command arguments are delimited with spaces.
|
|
|
|
Currently we support only one command. It travels from client to server.
|
|
|
|
EDIT [material id] [api index] [shader index] [shader length] [entire shader source....]
|
|
|
|
The `material id` is 8 hex digits.
|
|
|
|
The `api index` chooses between GL/VK/Metal and matches the values of the Backend enum (except that
|
|
zero is invalid).
|
|
|
|
The `shader index` is a zero-based index into the list of variants using the order that
|
|
they appear in the package, where each API (GL / VK / Metal) has its own list.
|
|
|
|
The `shader length` is the number of bytes required for UTF-8 encoding of the shader source string,
|
|
not including the terminating null.
|
|
|
|
## Wish List
|
|
|
|
- Allow editing of the original GLSL, perhaps by enhancing the `-g` option in matc and adding new chunk types.
|
|
- Port the web side to TypeScript
|
|
- This will clarify the structure of the pseudo-database, which is currently a total hack.
|
|
- Allows us to use enums instead of strings in several places (e.g. getShaderAPI)
|
|
- Try using https://github.com/basarat/typescript-script because webpack etc is painful.
|
|
- If the above idea is too slow then use https://github.com/evanw/esbuild.
|
|
- Expose the entire `engine.debug` struct in the web UI.
|
|
- When shader errors occur, send them back over the wire to the web client.
|
|
- Resizing the Chrome window causes layout issues.
|
|
- The sidebar in the web app is not resizeable.
|
|
- For the material ids, SHA-1 would be better than murmur since the latter can easily have collisions.
|
|
- It would be easy to add diff decorations to the editor in our `onEdit` function:
|
|
1. Examine "changes" (IModelContentChange) to get a set of line numbers.
|
|
2. `shader.decorations = gEditor.deltaDecorations(shader.decorations, ...)`
|
|
3. See [these monaco docs](https://microsoft.github.io/monaco-editor/playground.html#interacting-with-the-editor-line-and-inline-decorations).
|
|
|
|
## Screenshot
|
|
|
|
<img width="600px" src="https://user-images.githubusercontent.com/1288904/63553241-b043ba80-c4ee-11e9-816c-c6acb1d6cdf7.png">
|
|
|
|
[1]: https://github.com/civetweb/civetweb
|
|
[2]: https://microsoft.github.io/monaco-editor/
|
|
[3]: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/template
|
|
[4]: https://mustache.github.io/
|