ebiten/internal/graphicsdriver/opengl/graphics_linbsd.go

// Copyright 2022 The Ebitengine Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//go:build (freebsd || linux || netbsd || openbsd) && !android && !nintendosdk && !playstation5

package opengl

import (
	"bufio"
	"bytes"
	"os/exec"
	"strings"

	"github.com/hajimehoshi/ebiten/v2/internal/glfw"
	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/opengl/gl"
)

func isGLXExtensionForGL2Available() bool {
	var buf bytes.Buffer
	cmd := exec.Command("glxinfo")
	cmd.Stdout = &buf
	if err := cmd.Run(); err != nil {
		return false
	}

	const (
		indent = "    "
		ext    = "GLX_EXT_create_context_es2_profile"
	)

	var listingExtensions bool
	s := bufio.NewScanner(&buf)
	for s.Scan() {
		if !listingExtensions {
			if s.Text() == "GLX extensions:" {
				listingExtensions = true
			}
			continue
		}

		if !strings.HasPrefix(s.Text(), indent) {
			listingExtensions = false
			break
		}

		line := s.Text()
		for len(line) > 0 {
			head, tail, _ := strings.Cut(line, ",")
			if strings.TrimSpace(head) == ext {
				return true
			}
			line = tail
		}
	}
	return false
}

type graphicsPlatform struct {
	window *glfw.Window
}

// NewGraphics creates an implementation of graphicsdriver.Graphics for OpenGL.
// The returned graphics value is nil iff the error is not nil.
func NewGraphics() (graphicsdriver.Graphics, error) {
	ctx, err := gl.NewDefaultContext()
	if err != nil {
		return nil, err
	}

	if err := setGLFWClientAPI(ctx.IsES()); err != nil {
		return nil, err
	}

	return newGraphics(ctx), nil
}

func setGLFWClientAPI(isES bool) error {
	if isES {
		if err := glfw.WindowHint(glfw.ClientAPI, glfw.OpenGLESAPI); err != nil {
			return err
		}
		if err := glfw.WindowHint(glfw.ContextVersionMajor, 3); err != nil {
			return err
		}
		if err := glfw.WindowHint(glfw.ContextVersionMinor, 0); err != nil {
			return err
		}
		// Use GLX if the extension allows, or use EGL otherwise.
		// Prefer GLX since EGL might not work well on Wayland (#3152).
		if !isGLXExtensionForGL2Available() {
			if err := glfw.WindowHint(glfw.ContextCreationAPI, glfw.EGLContextAPI); err != nil {
				return err
			}
		}
		return nil
	}

	if err := glfw.WindowHint(glfw.ClientAPI, glfw.OpenGLAPI); err != nil {
		return err
	}
	if err := glfw.WindowHint(glfw.ContextVersionMajor, 3); err != nil {
		return err
	}
	if err := glfw.WindowHint(glfw.ContextVersionMinor, 2); err != nil {
		return err
	}
	return nil
}

func (g *Graphics) SetGLFWWindow(window *glfw.Window) {
	g.window = window
}

func (g *Graphics) makeContextCurrent() error {
	return g.window.MakeContextCurrent()
}

func (g *Graphics) swapBuffers() error {
	// Call SwapIntervals even though vsync is not changed.
	// When toggling to fullscreen, vsync state might be reset unexpectedly (#1787).

	// SwapInterval is affected by the current monitor of the window.
	// This needs to be called at least after SetMonitor.
	// Without SwapInterval after SetMonitor, vsynch doesn't work (#375).
	if g.vsync {
		if err := g.window.SwapInterval(1); err != nil {
			return err
		}
	} else {
		if err := g.window.SwapInterval(0); err != nil {
			return err
		}
	}

	if err := g.window.SwapBuffers(); err != nil {
		return err
	}
	return nil
}