From bc8bf9852d2323eb756069ad1bc4027f0c508130 Mon Sep 17 00:00:00 2001
From: Liam Galvin <liam.galvin@switchconcepts.com>
Date: Thu, 9 Aug 2018 14:07:10 +0100
Subject: [PATCH] efficient rendering with backgrounds

---
 gui/gui.go      | 23 ++++++++++++++++-------
 gui/renderer.go | 26 +++++++++++++++++---------
 2 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/gui/gui.go b/gui/gui.go
index 516bb14..d351d13 100644
--- a/gui/gui.go
+++ b/gui/gui.go
@@ -106,11 +106,22 @@ func (gui *GUI) Render() error {
 		return fmt.Errorf("Failed to load font: %s", err)
 	}
 
-	gui.renderer = NewOpenGLRenderer(gui.config, gui.font, gui.fontScale, 0, 0, gui.width, gui.height)
+	changeChan := make(chan bool, 1)
+	titleChan := make(chan bool, 1)
+
+	gui.renderer = NewOpenGLRenderer(gui.config, gui.font, gui.fontScale, 0, 0, gui.width, gui.height, gui.colourAttr, program)
 
 	gui.window.SetFramebufferSizeCallback(gui.resize)
 	gui.window.SetKeyCallback(gui.key)
 	gui.window.SetCharCallback(gui.char)
+	gui.window.SetFocusCallback(func(w *glfw.Window, focused bool) {
+		if focused {
+			select {
+			case changeChan <- true:
+			default:
+			}
+		}
+	})
 	w, h := gui.window.GetSize()
 	gui.resize(gui.window, w, h)
 
@@ -137,15 +148,12 @@ func (gui *GUI) Render() error {
 	//glfw.SwapInterval(1)
 
 	gl.ClearColor(
-		1.0, //gui.config.ColourScheme.DefaultBg[0],
+		gui.config.ColourScheme.DefaultBg[0],
 		gui.config.ColourScheme.DefaultBg[1],
 		gui.config.ColourScheme.DefaultBg[2],
 		1.0,
 	)
 
-	changeChan := make(chan bool, 1)
-	titleChan := make(chan bool, 1)
-
 	gui.terminal.AttachTitleChangeHandler(titleChan)
 	gui.terminal.AttachDisplayChangeHandler(changeChan)
 
@@ -191,12 +199,13 @@ func (gui *GUI) Render() error {
 			gui.font.Print(10, float32(gui.height-20), 1.5, fmt.Sprintf("%s", fpsData))
 		}
 
-		glfw.PollEvents()
-
 		if gui.config.Rendering.AlwaysRepaint || frames > 0 {
+			glfw.PollEvents()
 			frameCount++
 			gui.window.SwapBuffers()
 			frames--
+		} else {
+			glfw.WaitEventsTimeout(0.02) // every 20ms = 50fps on nothing changing
 		}
 	}
 
diff --git a/gui/renderer.go b/gui/renderer.go
index e01414c..1b9c4f2 100644
--- a/gui/renderer.go
+++ b/gui/renderer.go
@@ -31,6 +31,8 @@ type OpenGLRenderer struct {
 	cellPositions       map[[2]int][2]float32
 	rectangles          map[[2]int]*rectangle
 	config              config.Config
+	colourAttr          uint32
+	program             uint32
 }
 
 type rectangle struct {
@@ -42,7 +44,7 @@ type rectangle struct {
 	points     []float32
 }
 
-func (r *OpenGLRenderer) newRectangle(x float32, y float32) *rectangle {
+func (r *OpenGLRenderer) newRectangle(x float32, y float32, colourAttr uint32) *rectangle {
 
 	x = (x - float32(r.areaWidth/2)) / float32(r.areaWidth/2)
 	y = -(y - float32(r.areaHeight/2)) / float32(r.areaHeight/2)
@@ -59,6 +61,7 @@ func (r *OpenGLRenderer) newRectangle(x float32, y float32) *rectangle {
 			x + w, y + h, 0,
 			x + w, y, 0,
 		},
+		colourAttr: colourAttr,
 	}
 
 	rect.gen()
@@ -98,7 +101,7 @@ func (rect *rectangle) gen() {
 }
 
 func (rect *rectangle) setColour(colour [3]float32) {
-	if rect.colour == colour || true {
+	if rect.colour == colour {
 		return
 	}
 	rect.Free()
@@ -112,7 +115,7 @@ func (rect *rectangle) Free() {
 	gl.DeleteBuffers(1, &rect.cv)
 }
 
-func NewOpenGLRenderer(config config.Config, font *glfont.Font, fontScale int32, areaX int, areaY int, areaWidth int, areaHeight int) *OpenGLRenderer {
+func NewOpenGLRenderer(config config.Config, font *glfont.Font, fontScale int32, areaX int, areaY int, areaWidth int, areaHeight int, colourAttr uint32, program uint32) *OpenGLRenderer {
 	r := &OpenGLRenderer{
 		areaWidth:     areaWidth,
 		areaHeight:    areaHeight,
@@ -122,6 +125,8 @@ func NewOpenGLRenderer(config config.Config, font *glfont.Font, fontScale int32,
 		cellPositions: map[[2]int][2]float32{},
 		rectangles:    map[[2]int]*rectangle{},
 		config:        config,
+		colourAttr:    colourAttr,
+		program:       program,
 	}
 	r.SetFont(font)
 	return r
@@ -169,6 +174,7 @@ func (r *OpenGLRenderer) calculatePositions() {
 }
 
 func (r *OpenGLRenderer) generateRectangles() {
+	gl.UseProgram(r.program)
 	for line := 0; line < r.termRows; line++ {
 		for col := 0; col < r.termCols; col++ {
 
@@ -180,7 +186,7 @@ func (r *OpenGLRenderer) generateRectangles() {
 			// rounding to whole pixels makes everything nice
 			x := float32(float64((float32(col) * r.cellWidth)))
 			y := float32(float64((float32(line) * r.cellHeight) + (r.cellHeight)))
-			r.rectangles[[2]int{col, line}] = r.newRectangle(x, y)
+			r.rectangles[[2]int{col, line}] = r.newRectangle(x, y, r.colourAttr)
 		}
 	}
 }
@@ -218,12 +224,14 @@ func (r *OpenGLRenderer) DrawCell(cell *buffer.Cell, col int, row int) {
 		panic(fmt.Sprintf("Missing rectangle data for cell at %d,%d", col, row))
 	}
 
-	//rect.setColour(bg)
-	_ = bg
-	rect.setColour([3]float32{0, 0, 1})
+	// don't bother rendering rectangles that are the same colour as the background
+	if bg != r.config.ColourScheme.DefaultBg {
+		rect.setColour(bg)
 
-	gl.BindVertexArray(rect.vao)
-	gl.DrawArrays(gl.TRIANGLES, 0, 6)
+		gl.UseProgram(r.program)
+		gl.BindVertexArray(rect.vao)
+		gl.DrawArrays(gl.TRIANGLES, 0, 6)
+	}
 
 	if cell.Attr().Bold { // bold means draw text again one pixel to right, so it's fatter
 		r.font.Print(pos[0]+1, pos[1], 1, string(cell.Rune()))