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