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- // Copyright 2014 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- /*
- Package gl implements Go bindings for OpenGL ES 2.0 and ES 3.0.
- The GL functions are defined on a Context object that is responsible for
- tracking a GL context. Typically a windowing system package (such as
- golang.org/x/exp/shiny/screen) will call NewContext and provide
- a gl.Context for a user application.
- If the gl package is compiled on a platform capable of supporting ES 3.0,
- the gl.Context object also implements gl.Context3.
- The bindings are deliberately minimal, staying as close the C API as
- possible. The semantics of each function maps onto functions
- described in the Khronos documentation:
- https://www.khronos.org/opengles/sdk/docs/man/
- One notable departure from the C API is the introduction of types
- to represent common uses of GLint: Texture, Surface, Buffer, etc.
- # Debug Logging
- A tracing version of the OpenGL bindings is behind the `gldebug` build
- tag. It acts as a simplified version of apitrace. Build your Go binary
- with
- -tags gldebug
- and each call to a GL function will log its input, output, and any
- error messages. For example,
- I/GoLog (27668): gl.GenBuffers(1) [Buffer(70001)]
- I/GoLog (27668): gl.BindBuffer(ARRAY_BUFFER, Buffer(70001))
- I/GoLog (27668): gl.BufferData(ARRAY_BUFFER, 36, len(36), STATIC_DRAW)
- I/GoLog (27668): gl.BindBuffer(ARRAY_BUFFER, Buffer(70001))
- I/GoLog (27668): gl.VertexAttribPointer(Attrib(0), 6, FLOAT, false, 0, 0) error: [INVALID_VALUE]
- The gldebug tracing has very high overhead, so make sure to remove
- the build tag before deploying any binaries.
- */
- package gl
- /*
- Implementation details.
- All GL function calls fill out a C.struct_fnargs and drop it on the work
- queue. The Start function drains the work queue and hands over a batch
- of calls to C.process which runs them. This allows multiple GL calls to
- be executed in a single cgo call.
- A GL call is marked as blocking if it returns a value, or if it takes a
- Go pointer. In this case the call will not return until C.process sends a
- value on the retvalue channel.
- This implementation ensures any goroutine can make GL calls, but it does
- not make the GL interface safe for simultaneous use by multiple goroutines.
- For the purpose of analyzing this code for race conditions, picture two
- separate goroutines: one blocked on gl.Start, and another making calls to
- the gl package exported functions.
- */
- //go:generate go run gendebug.go -o gldebug.go
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