added a glfwcanvas subpackage

README.md

@@ -10,15 +10,15 @@ Whereas the Javascript API uses a context that all draw calls go to, here all dr
 
 The library is intended to provide decent performance. Obviously it will not be able to rival hand coded OpenGL for a given purpose, but for many purposes it will be enough. It can also be combined with hand coded OpenGL.
 
-# SDL convenience package
+# SDL/GLFW convenience packages
 
-The sdlcanvas subpackage provides a very simple way to get started with just a few lines of code. As the name implies it is based on the SDL library. It creates a window for you and gives you a canvas to draw with.
+The sdlcanvas and glfwcanvas subpackages provide a very simple way to get started with just a few lines of code. As the names imply they are based on the SDL library and the GLFW library respectively. They create a window for you and give you a canvas to draw with.
 
 # OS support
 
 - Linux
 - Windows
-- OSX
+- macOS
 - Android
 - iOS
 

examples/glfw/glfw.go

@@ -13,7 +13,7 @@ import (
 func main() {
 	runtime.LockOSThread()
 
-	// init SDL
+	// init GLFW
 	err := glfw.Init()
 	if err != nil {
 		log.Fatalf("Error initializing GLFW: %v", err)

glfwcanvas/glfwcanvas.go

@@ -0,0 +1,167 @@
+package glfwcanvas
+
+import (
+	"fmt"
+	_ "image/gif" // Imported here so that applications based on this package support these formats by default
+	_ "image/jpeg"
+	_ "image/png"
+	"log"
+	"math"
+	"runtime"
+	"time"
+
+	"github.com/go-gl/gl/v3.2-core/gl"
+	"github.com/go-gl/glfw/v3.2/glfw"
+	"github.com/tfriedel6/canvas"
+	"github.com/tfriedel6/canvas/glimpl/gogl"
+)
+
+// Window represents the opened window with GL context. The Mouse* and Key*
+// functions can be set for callbacks
+type Window struct {
+	Window     *glfw.Window
+	canvas     *canvas.Canvas
+	frameTimes [10]time.Time
+	frameIndex int
+	frameCount int
+	fps        float32
+	close      bool
+	MouseDown  func(button, x, y int)
+	MouseMove  func(x, y int)
+	MouseUp    func(button, x, y int)
+	MouseWheel func(x, y int)
+	KeyDown    func(scancode int, rn rune, name string)
+	KeyUp      func(scancode int, rn rune, name string)
+	KeyChar    func(rn rune)
+	SizeChange func(w, h int)
+}
+
+// CreateWindow creates a window using SDL and initializes the OpenGL context
+func CreateWindow(w, h int, title string) (*Window, *canvas.Canvas, error) {
+	runtime.LockOSThread()
+
+	// init GLFW
+	err := glfw.Init()
+	if err != nil {
+		log.Fatalf("Error initializing GLFW: %v", err)
+	}
+
+	// the stencil size setting is required for the canvas to work
+	glfw.WindowHint(glfw.StencilBits, 8)
+	glfw.WindowHint(glfw.DepthBits, 0)
+
+	// create window
+	window, err := glfw.CreateWindow(w, h, title, nil, nil)
+	if err != nil {
+		log.Fatalf("Error creating window: %v", err)
+	}
+	window.MakeContextCurrent()
+
+	// init GL
+	err = gl.Init()
+	if err != nil {
+		log.Fatalf("Error initializing GL: %v", err)
+	}
+
+	// set vsync on, enable multisample (if available)
+	glfw.SwapInterval(1)
+	gl.Enable(gl.MULTISAMPLE)
+
+	// load canvas GL assets
+	err = canvas.LoadGL(glimplgogl.GLImpl{})
+	if err != nil {
+		log.Fatalf("Error loading canvas GL assets: %v", err)
+	}
+
+	err = canvas.LoadGL(glimplgogl.GLImpl{})
+	if err != nil {
+		return nil, nil, fmt.Errorf("Error loading canvas GL assets: %v", err)
+	}
+
+	cv := canvas.New(0, 0, w, h)
+	wnd := &Window{
+		Window: window,
+		canvas: cv,
+	}
+
+	var mx, my int
+
+	window.SetMouseButtonCallback(func(w *glfw.Window, button glfw.MouseButton, action glfw.Action, mod glfw.ModifierKey) {
+		if action == glfw.Press && wnd.MouseDown != nil {
+			wnd.MouseDown(int(button), mx, my)
+		} else if action == glfw.Release && wnd.MouseUp != nil {
+			wnd.MouseUp(int(button), mx, my)
+		}
+	})
+	window.SetCursorPosCallback(func(w *glfw.Window, xpos float64, ypos float64) {
+		mx, my = int(math.Round(xpos)), int(math.Round(ypos))
+		if wnd.MouseMove != nil {
+			wnd.MouseMove(mx, my)
+		}
+	})
+	window.SetScrollCallback(func(w *glfw.Window, xoff float64, yoff float64) {
+		if wnd.MouseWheel != nil {
+			wnd.MouseWheel(int(math.Round(xoff)), int(math.Round(yoff)))
+		}
+	})
+	window.SetKeyCallback(func(w *glfw.Window, key glfw.Key, scancode int, action glfw.Action, mods glfw.ModifierKey) {
+		if action == glfw.Press && wnd.KeyDown != nil {
+			wnd.KeyDown(scancode, keyRune(key), keyName(key))
+		} else if action == glfw.Release && wnd.KeyUp != nil {
+			wnd.KeyUp(scancode, keyRune(key), keyName(key))
+		}
+	})
+	window.SetCharCallback(func(w *glfw.Window, char rune) {
+		if wnd.KeyChar != nil {
+			wnd.KeyChar(char)
+		}
+	})
+	window.SetSizeCallback(func(w *glfw.Window, width int, height int) {
+		if wnd.SizeChange != nil {
+			wnd.SizeChange(width, height)
+		}
+	})
+
+	return wnd, cv, nil
+}
+
+// FPS returns the frames per second (averaged over 10 frames)
+func (wnd *Window) FPS() float32 {
+	return wnd.fps
+}
+
+// Close can be used to end a call to MainLoop
+func (wnd *Window) Close() {
+	wnd.close = true
+}
+
+// StartFrame handles events and gets the window ready for rendering
+func (wnd *Window) StartFrame() {
+	wnd.Window.MakeContextCurrent()
+	glfw.PollEvents()
+}
+
+// FinishFrame updates the FPS count and displays the frame
+func (wnd *Window) FinishFrame() {
+	now := time.Now()
+	wnd.frameTimes[wnd.frameIndex] = now
+	wnd.frameIndex++
+	wnd.frameIndex %= len(wnd.frameTimes)
+	if wnd.frameCount < len(wnd.frameTimes) {
+		wnd.frameCount++
+	} else {
+		diff := now.Sub(wnd.frameTimes[wnd.frameIndex]).Seconds()
+		wnd.fps = float32(wnd.frameCount-1) / float32(diff)
+	}
+
+	wnd.Window.SwapBuffers()
+}
+
+// MainLoop runs a main loop and calls run on every frame
+func (wnd *Window) MainLoop(run func()) {
+	for !wnd.close {
+		wnd.StartFrame()
+		run()
+		wnd.FinishFrame()
+	}
+}

glfwcanvas/keynames.go

@@ -0,0 +1,216 @@
+package glfwcanvas
+
+import "github.com/go-gl/glfw/v3.2/glfw"
+
+var keyNameMap [347]string
+var keyRuneMap [347]rune
+
+func init() {
+	keyNameMap[glfw.KeyEscape] = "Escape"
+	keyNameMap[glfw.Key0] = "Digit0"
+	keyNameMap[glfw.Key1] = "Digit1"
+	keyNameMap[glfw.Key2] = "Digit2"
+	keyNameMap[glfw.Key3] = "Digit3"
+	keyNameMap[glfw.Key4] = "Digit4"
+	keyNameMap[glfw.Key5] = "Digit5"
+	keyNameMap[glfw.Key6] = "Digit6"
+	keyNameMap[glfw.Key7] = "Digit7"
+	keyNameMap[glfw.Key8] = "Digit8"
+	keyNameMap[glfw.Key9] = "Digit9"
+	keyNameMap[glfw.KeyMinus] = "Minus"
+	keyNameMap[glfw.KeyEqual] = "Equal"
+	keyNameMap[glfw.KeyBackspace] = "Backspace"
+	keyNameMap[glfw.KeyTab] = "Tab"
+	keyNameMap[glfw.KeyQ] = "KeyQ"
+	keyNameMap[glfw.KeyW] = "KeyW"
+	keyNameMap[glfw.KeyE] = "KeyE"
+	keyNameMap[glfw.KeyR] = "KeyR"
+	keyNameMap[glfw.KeyT] = "KeyT"
+	keyNameMap[glfw.KeyY] = "KeyY"
+	keyNameMap[glfw.KeyU] = "KeyU"
+	keyNameMap[glfw.KeyI] = "KeyI"
+	keyNameMap[glfw.KeyO] = "KeyO"
+	keyNameMap[glfw.KeyP] = "KeyP"
+	keyNameMap[glfw.KeyLeftBracket] = "BracketLeft"
+	keyNameMap[glfw.KeyRightBracket] = "BracketRight"
+	keyNameMap[glfw.KeyEnter] = "Enter"
+	keyNameMap[glfw.KeyLeftControl] = "ControlLeft"
+	keyNameMap[glfw.KeyA] = "KeyA"
+	keyNameMap[glfw.KeyS] = "KeyS"
+	keyNameMap[glfw.KeyD] = "KeyD"
+	keyNameMap[glfw.KeyF] = "KeyF"
+	keyNameMap[glfw.KeyG] = "KeyG"
+	keyNameMap[glfw.KeyH] = "KeyH"
+	keyNameMap[glfw.KeyJ] = "KeyJ"
+	keyNameMap[glfw.KeyK] = "KeyK"
+	keyNameMap[glfw.KeyL] = "KeyL"
+	keyNameMap[glfw.KeySemicolon] = "Semicolon"
+	keyNameMap[glfw.KeyApostrophe] = "Quote"
+	keyNameMap[glfw.KeyGraveAccent] = "Backquote"
+	keyNameMap[glfw.KeyLeftShift] = "ShiftLeft"
+	keyNameMap[glfw.KeyBackslash] = "Backslash"
+	keyNameMap[glfw.KeyZ] = "KeyZ"
+	keyNameMap[glfw.KeyX] = "KeyX"
+	keyNameMap[glfw.KeyC] = "KeyC"
+	keyNameMap[glfw.KeyV] = "KeyV"
+	keyNameMap[glfw.KeyB] = "KeyB"
+	keyNameMap[glfw.KeyN] = "KeyN"
+	keyNameMap[glfw.KeyM] = "KeyM"
+	keyNameMap[glfw.KeyComma] = "Comma"
+	keyNameMap[glfw.KeyPeriod] = "Period"
+	keyNameMap[glfw.KeySlash] = "Slash"
+	keyNameMap[glfw.KeyRightShift] = "RightShift"
+	keyNameMap[glfw.KeyKPMultiply] = "NumpadMultiply"
+	keyNameMap[glfw.KeyLeftAlt] = "AltLeft"
+	keyNameMap[glfw.KeySpace] = "Space"
+	keyNameMap[glfw.KeyCapsLock] = "CapsLock"
+	keyNameMap[glfw.KeyF1] = "F1"
+	keyNameMap[glfw.KeyF2] = "F2"
+	keyNameMap[glfw.KeyF3] = "F3"
+	keyNameMap[glfw.KeyF4] = "F4"
+	keyNameMap[glfw.KeyF5] = "F5"
+	keyNameMap[glfw.KeyF6] = "F6"
+	keyNameMap[glfw.KeyF7] = "F7"
+	keyNameMap[glfw.KeyF8] = "F8"
+	keyNameMap[glfw.KeyF9] = "F9"
+	keyNameMap[glfw.KeyF10] = "F10"
+	keyNameMap[glfw.KeyPause] = "Pause"
+	keyNameMap[glfw.KeyScrollLock] = "ScrollLock"
+	keyNameMap[glfw.KeyKP7] = "Numpad7"
+	keyNameMap[glfw.KeyKP8] = "Numpad8"
+	keyNameMap[glfw.KeyKP9] = "Numpad9"
+	keyNameMap[glfw.KeyKPSubtract] = "NumpadSubtract"
+	keyNameMap[glfw.KeyKP4] = "Numpad4"
+	keyNameMap[glfw.KeyKP5] = "Numpad5"
+	keyNameMap[glfw.KeyKP6] = "Numpad6"
+	keyNameMap[glfw.KeyKPAdd] = "NumpadAdd"
+	keyNameMap[glfw.KeyKP1] = "Numpad1"
+	keyNameMap[glfw.KeyKP2] = "Numpad2"
+	keyNameMap[glfw.KeyKP3] = "Numpad3"
+	keyNameMap[glfw.KeyKP0] = "Numpad0"
+	keyNameMap[glfw.KeyKPDecimal] = "NumpadDecimal"
+	keyNameMap[glfw.KeyPrintScreen] = "PrintScreen"
+	// keyNameMap[glfw.KeyNonUSBackslash] = "IntlBackslash"
+	keyNameMap[glfw.KeyF11] = "F11"
+	keyNameMap[glfw.KeyF12] = "F12"
+	keyNameMap[glfw.KeyKPEqual] = "NumpadEqual"
+	keyNameMap[glfw.KeyF13] = "F13"
+	keyNameMap[glfw.KeyF14] = "F14"
+	keyNameMap[glfw.KeyF15] = "F15"
+	keyNameMap[glfw.KeyF16] = "F16"
+	keyNameMap[glfw.KeyF17] = "F17"
+	keyNameMap[glfw.KeyF18] = "F18"
+	keyNameMap[glfw.KeyF19] = "F19"
+	// keyNameMap[glfw.KeyUndo] = "Undo"
+	// keyNameMap[glfw.KeyPaste] = "Paste"
+	// keyNameMap[glfw.KeyAudioNext] = "MediaTrackPrevious"
+	// keyNameMap[glfw.KeyCut] = "Cut"
+	// keyNameMap[glfw.KeyCopy] = "Copy"
+	// keyNameMap[glfw.KeyAudioNext] = "MediaTrackNext"
+	keyNameMap[glfw.KeyKPEnter] = "NumpadEnter"
+	keyNameMap[glfw.KeyRightControl] = "ControlRight"
+	// keyNameMap[glfw.KeyMute] = "AudioVolumeMute"
+	// keyNameMap[glfw.KeyAudioPlay] = "MediaPlayPause"
+	// keyNameMap[glfw.KeyAudioStop] = "MediaStop"
+	// keyNameMap[glfw.KeyVolumeDown] = "AudioVolumeDown"
+	// keyNameMap[glfw.KeyVolumeUp] = "AudioVolumeUp"
+	keyNameMap[glfw.KeyKPDivide] = "NumpadDivide"
+	keyNameMap[glfw.KeyRightAlt] = "AltRight"
+	// keyNameMap[glfw.KeyHelp] = "Help"
+	keyNameMap[glfw.KeyHome] = "Home"
+	keyNameMap[glfw.KeyUp] = "ArrowUp"
+	keyNameMap[glfw.KeyPageUp] = "PageUp"
+	keyNameMap[glfw.KeyLeft] = "ArrowLeft"
+	keyNameMap[glfw.KeyRight] = "ArrowRight"
+	keyNameMap[glfw.KeyEnd] = "End"
+	keyNameMap[glfw.KeyDown] = "ArrowDown"
+	keyNameMap[glfw.KeyInsert] = "Insert"
+	keyNameMap[glfw.KeyDelete] = "Delete"
+	// keyNameMap[glfw.KeyApplication] = "ContextMenu"
+
+	keyRuneMap[glfw.Key0] = '0'
+	keyRuneMap[glfw.Key1] = '1'
+	keyRuneMap[glfw.Key2] = '2'
+	keyRuneMap[glfw.Key3] = '3'
+	keyRuneMap[glfw.Key4] = '4'
+	keyRuneMap[glfw.Key5] = '5'
+	keyRuneMap[glfw.Key6] = '6'
+	keyRuneMap[glfw.Key7] = '7'
+	keyRuneMap[glfw.Key8] = '8'
+	keyRuneMap[glfw.Key9] = '9'
+	keyRuneMap[glfw.KeyMinus] = '-'
+	keyRuneMap[glfw.KeyEqual] = '='
+	keyRuneMap[glfw.KeyTab] = '\t'
+	keyRuneMap[glfw.KeyQ] = 'Q'
+	keyRuneMap[glfw.KeyW] = 'W'
+	keyRuneMap[glfw.KeyE] = 'E'
+	keyRuneMap[glfw.KeyR] = 'R'
+	keyRuneMap[glfw.KeyT] = 'T'
+	keyRuneMap[glfw.KeyY] = 'Y'
+	keyRuneMap[glfw.KeyU] = 'U'
+	keyRuneMap[glfw.KeyI] = 'I'
+	keyRuneMap[glfw.KeyO] = 'O'
+	keyRuneMap[glfw.KeyP] = 'P'
+	keyRuneMap[glfw.KeyLeftBracket] = '['
+	keyRuneMap[glfw.KeyRightBracket] = ']'
+	keyRuneMap[glfw.KeyEnter] = '\n'
+	keyRuneMap[glfw.KeyA] = 'A'
+	keyRuneMap[glfw.KeyS] = 'S'
+	keyRuneMap[glfw.KeyD] = 'D'
+	keyRuneMap[glfw.KeyF] = 'F'
+	keyRuneMap[glfw.KeyG] = 'G'
+	keyRuneMap[glfw.KeyH] = 'H'
+	keyRuneMap[glfw.KeyJ] = 'J'
+	keyRuneMap[glfw.KeyK] = 'K'
+	keyRuneMap[glfw.KeyL] = 'L'
+	keyRuneMap[glfw.KeySemicolon] = ';'
+	keyRuneMap[glfw.KeyApostrophe] = '\''
+	keyRuneMap[glfw.KeyGraveAccent] = '`'
+	keyRuneMap[glfw.KeyBackslash] = '\\'
+	keyRuneMap[glfw.KeyZ] = 'Z'
+	keyRuneMap[glfw.KeyX] = 'X'
+	keyRuneMap[glfw.KeyC] = 'C'
+	keyRuneMap[glfw.KeyV] = 'V'
+	keyRuneMap[glfw.KeyB] = 'B'
+	keyRuneMap[glfw.KeyN] = 'N'
+	keyRuneMap[glfw.KeyM] = 'M'
+	keyRuneMap[glfw.KeyComma] = ','
+	keyRuneMap[glfw.KeyPeriod] = '.'
+	keyRuneMap[glfw.KeySlash] = '/'
+	keyRuneMap[glfw.KeyKPMultiply] = '*'
+	keyRuneMap[glfw.KeySpace] = ' '
+	keyRuneMap[glfw.KeyKP7] = '7'
+	keyRuneMap[glfw.KeyKP8] = '8'
+	keyRuneMap[glfw.KeyKP9] = '9'
+	keyRuneMap[glfw.KeyKPSubtract] = '-'
+	keyRuneMap[glfw.KeyKP4] = '4'
+	keyRuneMap[glfw.KeyKP5] = '5'
+	keyRuneMap[glfw.KeyKP6] = '6'
+	keyRuneMap[glfw.KeyKPAdd] = '+'
+	keyRuneMap[glfw.KeyKP1] = '1'
+	keyRuneMap[glfw.KeyKP2] = '2'
+	keyRuneMap[glfw.KeyKP3] = '3'
+	keyRuneMap[glfw.KeyKP0] = '0'
+	keyRuneMap[glfw.KeyKPDecimal] = '.'
+	keyRuneMap[glfw.KeyKPEqual] = '='
+	keyRuneMap[glfw.KeyKPEnter] = '\n'
+	keyRuneMap[glfw.KeyKPDivide] = '/'
+}
+
+func keyName(key glfw.Key) string {
+	if int(key) >= len(keyNameMap) {
+		return "Unidentified"
+	}
+	name := keyNameMap[key]
+	if name == "" {
+		return "Unidentified"
+	}
+	return name
+}
+
+func keyRune(key glfw.Key) rune {
+	if int(key) >= len(keyNameMap) {
+		return 0
+	}
+	return keyRuneMap[key]
+}