I am using the same OpenGL code written in Golang to draw two lines in a 640x480 pixel space. I am puzzled because both lines are drawn correctly in Linux, but only one of them is drawn in Windows10. What could cause that difference in OpenGL behavior?

Line 1: 0,0 - 639,479 (works only on Linux)
Line 2: 50,0 - 0,50 (works on both Linux and Windows10)

On Linux, both Lines are drawn correctly:

App logs from Linux:

2019/08/15 02:44:12 requesting window for OpenGL 3.3
2019/08/15 02:44:12 graphicsStart(9): 640 x 480
2019/08/15 02:44:12 OpenGL version 3.3 (Core Profile) Mesa 18.2.8
2019/08/15 02:44:12 OpenGL program: 3
2019/08/15 02:44:12 pixelToClip: 0 x 0 => -1.000000 x 1.000000
2019/08/15 02:44:12 pixelToClip: 639 x 479 => 1.000000 x -1.000000
2019/08/15 02:44:12 pixelToClip: 50 x 0 => -0.843506 x 1.000000
2019/08/15 02:44:12 pixelToClip: 0 x 50 => -1.000000 x 0.791232

On Windows10, only the second line is drawn:

App logs from Windows10:

2019/08/15 18:41:19 requesting window for OpenGL 3.3
2019/08/15 18:41:19 graphicsStart(9): 640 x 480
2019/08/15 18:41:19 OpenGL version 3.3.0 - Build 21.20.16.4627
2019/08/15 18:41:19 OpenGL program: 3
2019/08/15 18:41:19 pixelToClip: 0 x 0 => -1.000000 x 1.000000
2019/08/15 18:41:19 pixelToClip: 639 x 479 => 1.000000 x -1.000000
2019/08/15 18:41:19 pixelToClip: 50 x 0 => -0.843506 x 1.000000
2019/08/15 18:41:19 pixelToClip: 0 x 50 => -1.000000 x 0.791232

This is the full source code for the app:

$ cat a.go
// # recipe for running a.go (Go 1.11 or higher)
// mkdir tmp                                    ;# create dir for module
// cp a.go tmp                                  ;# put app in dir
// cd tmp                                       ;# enter dir
// go mod init tmp                              ;# init module
// go get -u github.com/udhos/basgo@mainthread  ;# get lib from branch mainthread
// go run a.go                                  ;# run

package main

import (
        "github.com/faiface/mainthread"
        "github.com/udhos/basgo/baslib"
)

func main() {
        mainthread.Run(run)
}

func run() {
        mainthread.Call(func() {
                baslib.G = baslib.InitWin(640, 480)
        })
        baslib.Cls()
        baslib.Screen(9)
        baslib.Color(7, 5)
        baslib.Line(0, 0, 639, 479, -1, -1) // Line 1 (only linux)
        baslib.Line(50, 0, 0, 50, -1, -1)   // Line 2 (linux + windows)
        baslib.Print(baslib.InputCount(1))  // wait keyboard
        baslib.Println(``)
        baslib.Cls()
        baslib.Color(2, -1)
        for i := 50; i <= 300; i++ {
                baslib.Line(100, 50, 319, i, -1, -1)
        }
        baslib.Color(4, -1)
        baslib.LineBox(10, 100, 40, 130, 1, -1, false)
        baslib.LineBox(15, 105, 35, 125, -1, -1, true)
        baslib.LineBox(80, 130, 50, 100, 1, -1, false)
        baslib.LineBox(75, 125, 55, 105, -1, -1, true)
        baslib.LineBox(40, 140, 10, 170, 1, -1, false)
        baslib.LineBox(15, 165, 35, 145, -1, -1, true)
        baslib.LineBox(50, 170, 80, 140, 1, -1, false)
        baslib.LineBox(55, 165, 75, 145, -1, -1, true)
        baslib.Print(baslib.InputCount(1)) // wait keyboard
        baslib.Println(``)
}

Function baslib.Line() is the main portion responsible for the draw, and it is available here:

https://github.com/udhos/basgo/blob/mainthread/baslib/graphics.go#L269

基于OpenGL的三维地图可视化移动客户端设计上的问题

w12q33

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