Add clear and glclear tools (#88)

Author: elgopher

examples/tools/clear/clear.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"github.com/jacekolszak/pixiq/colornames"
+	"github.com/jacekolszak/pixiq/image"
+	"github.com/jacekolszak/pixiq/keyboard"
+	"github.com/jacekolszak/pixiq/loop"
+	"github.com/jacekolszak/pixiq/opengl"
+	"github.com/jacekolszak/pixiq/tools/clear"
+	"github.com/jacekolszak/pixiq/tools/glclear"
+)
+
+type clearTool interface {
+	SetColor(image.Color)
+	Clear(image.Selection)
+}
+
+func main() {
+	opengl.RunOrDie(func(gl *opengl.OpenGL) {
+		window, err := gl.OpenWindow(10, 10, opengl.Zoom(30))
+		if err != nil {
+			panic(err)
+		}
+		context := gl.Context()
+		tools := []clearTool{
+			glclear.New(context.NewClearCommand()), // GPU one
+			clear.New(),                            // CPU one
+		}
+		tools[0].SetColor(colornames.Cornflowerblue)
+		tools[1].SetColor(colornames.Hotpink)
+		currentTool := 0
+		keys := keyboard.New(window)
+		loop.Run(window, func(frame *loop.Frame) {
+			screen := frame.Screen()
+			var (
+				leftEye  = screen.Selection(2, 2).WithSize(2, 2)
+				rightEye = screen.Selection(6, 2).WithSize(2, 2)
+				nose     = screen.Selection(4, 5).WithSize(2, 2)
+				mouth    = screen.Selection(2, 8).WithSize(6, 1)
+			)
+			tool := tools[currentTool]
+			tool.Clear(leftEye)
+			tool.Clear(rightEye)
+			tool.Clear(nose)
+			tool.Clear(mouth)
+			keys.Update()
+			if keys.JustReleased(keyboard.Space) {
+				currentTool++
+				currentTool = currentTool % len(tools)
+			}
+		})
+
+	})
+}

gl/command.go

@@ -199,7 +199,7 @@ func (c *AcceleratedCommand) Run(output image.AcceleratedImageSelection, selecti
 		panic("output image created in a different OpenGL context than program")
 	}
 
-	c.api.UseProgram(c.program.id)
+	c.program.use()
 	c.api.Enable(scissorTest)
 	c.api.BindFramebuffer(framebuffer, img.frameBufferID)
 	loc := output.Location

gl/context.go

@@ -2,6 +2,8 @@ package gl
 
 import (
 	"fmt"
+
+	"github.com/jacekolszak/pixiq/image"
 )
 
 // Context is an OpenGL context
@@ -275,3 +277,40 @@ func (p *Program) AcceleratedCommand(command Command) *AcceleratedCommand {
 func (p *Program) ID() uint32 {
 	return p.id
 }
+
+func (p *Program) use() {
+	if p.program != nil {
+		p.api.UseProgram(p.id)
+	}
+}
+
+// NewClearCommand returns a command clearing all pixels in image.Selection
+func (c *Context) NewClearCommand() *ClearCommand {
+	nilProgram := &Program{
+		program:          nil,
+		uniformLocations: map[string]int32{},
+		attributes:       map[int32]attribute{},
+		api:              c.api,
+		allImages:        c.allImages,
+	}
+	cmd := &ClearCommand{}
+	cmd.AcceleratedCommand = nilProgram.AcceleratedCommand(cmd)
+	return cmd
+}
+
+// ClearCommand clears the image.Selection using given color. By default color
+// is transparent.
+type ClearCommand struct {
+	*AcceleratedCommand
+	color image.Color
+}
+
+// SetColor sets color which will be used to clear all pixels in image.Selection
+func (c *ClearCommand) SetColor(color image.Color) {
+	c.color = color
+}
+
+// RunGL implements gl.Command
+func (c *ClearCommand) RunGL(renderer *Renderer, _ []image.AcceleratedImageSelection) {
+	renderer.Clear(c.color)
+}

gl/image.go

@@ -51,6 +51,8 @@ func (c *Context) NewAcceleratedImage(width, height int) *AcceleratedImage {
 		api:           c.api,
 	}
 	c.allImages[img] = img
+	clearWithTransparentColor := c.NewClearCommand()
+	clearWithTransparentColor.Run(img.wholeSelection(), []image.AcceleratedImageSelection{})
 	return img
 }
 
@@ -63,6 +65,13 @@ type AcceleratedImage struct {
 	api           API
 }
 
+func (i *AcceleratedImage) wholeSelection() image.AcceleratedImageSelection {
+	return image.AcceleratedImageSelection{
+		Location: image.AcceleratedImageLocation{Width: i.width, Height: i.height},
+		Image:    i,
+	}
+}
+
 // TextureID returns texture identifier (aka name)
 func (i *AcceleratedImage) TextureID() uint32 {
 	return i.textureID

gl/integration/opengl/opengl_bench_test.go

@@ -3,12 +3,16 @@ package opengl_test
 import (
 	"testing"
 
+	"github.com/stretchr/testify/require"
+
 	"github.com/jacekolszak/pixiq/image"
 	"github.com/jacekolszak/pixiq/opengl"
 )
 
 func BenchmarkAcceleratedImage_Upload(b *testing.B) {
 	openGL, err := opengl.New(mainThreadLoop)
+	require.NoError(b, err)
+	defer openGL.Destroy()
 	if err != nil {
 		panic(err)
 	}