Reduce panics (#16)

ebitenutil/debugprint.go

@@ -64,15 +64,16 @@ func (d *debugPrintState) drawText(rt *ebiten.Image, str string, x, y int, c col
 	})
 }
 
-func (d *debugPrintState) DebugPrint(r *ebiten.Image, str string) {
+// DebugPrint prints the given text str on the given image r.
+func (d *debugPrintState) DebugPrint(r *ebiten.Image, str string) error {
 	if d.textImage == nil {
 		img, err := assets.TextImage()
 		if err != nil {
-			panic(err)
+			return err
 		}
 		d.textImage, err = ebiten.NewImageFromImage(img, ebiten.FilterNearest)
 		if err != nil {
-			panic(err)
+			return err
 		}
 	}
 	if d.debugPrintRenderTarget == nil {
@@ -80,9 +81,10 @@ func (d *debugPrintState) DebugPrint(r *ebiten.Image, str string) {
 		var err error
 		d.debugPrintRenderTarget, err = ebiten.NewImage(width, height, ebiten.FilterNearest)
 		if err != nil {
-			panic(err)
+			return err
 		}
 	}
 	d.drawText(r, str, 1, d.y+1, color.NRGBA{0x00, 0x00, 0x00, 0x80})
 	d.drawText(r, str, 0, d.y, color.NRGBA{0xff, 0xff, 0xff, 0xff})
+	return nil
 }

image.go

@@ -75,8 +75,7 @@ func (i *innerImage) drawImage(img *innerImage, options *DrawImageOptions) error
 	w, h := img.texture.Size()
 	quads := textureQuads(parts, w, h)
 	projectionMatrix := i.framebuffer.ProjectionMatrix()
-	shader.DrawTexture(img.texture.Native(), projectionMatrix, quads, geo, clr)
+	return shader.DrawTexture(img.texture.Native(), projectionMatrix, quads, geo, clr)
-	return nil
 }
 
 func u(x float64, width int) float32 {
@@ -200,7 +199,7 @@ type ImagePart struct {
 	Src image.Rectangle
 }
 
-// A DrawImageOptions presents options to render an image on an image.
+// A DrawImageOptions represents options to render an image on an image.
 type DrawImageOptions struct {
 	Parts  []ImagePart
 	GeoM   GeoM

internal/opengl/internal/shader/drawtexture.go

@@ -40,11 +40,13 @@ const size = 10000
 const uint16Size = 2
 const short32Size = 4
 
-func DrawTexture(native gl.Texture, projectionMatrix [4][4]float64, quads []TextureQuad, geo Matrix, color Matrix) {
+func DrawTexture(native gl.Texture, projectionMatrix [4][4]float64, quads []TextureQuad, geo Matrix, color Matrix) error {
 	// TODO: Check len(quads) and gl.MAX_ELEMENTS_INDICES?
 	const stride = 4 * 4
 	if !initialized {
-		initialize()
+		if err := initialize(); err != nil {
+			return err
+		}
 
 		vertexBuffer := gl.GenBuffer()
 		vertexBuffer.Bind(gl.ARRAY_BUFFER)
@@ -68,7 +70,7 @@ func DrawTexture(native gl.Texture, projectionMatrix [4][4]float64, quads []Text
 	}
 
 	if len(quads) == 0 {
-		return
+		return nil
 	}
 	// TODO: Check performance
 	program := useProgramColorMatrix(glMatrix(projectionMatrix), geo, color)
@@ -110,4 +112,5 @@ func DrawTexture(native gl.Texture, projectionMatrix [4][4]float64, quads []Text
 	gl.DrawElements(gl.TRIANGLES, 6*len(quads), gl.UNSIGNED_SHORT, uintptr(0))
 
 	gl.Flush()
+	return nil
 }

internal/opengl/internal/shader/program.go

@@ -15,6 +15,7 @@
 package shader
 
 import (
+	"errors"
 	"github.com/go-gl/gl"
 )
 
@@ -27,10 +28,10 @@ var programColorMatrix = program{
 	shaderIds: []shaderId{shaderVertex, shaderColorMatrix},
 }
 
-func (p *program) create() {
+func (p *program) create() error {
 	p.native = gl.CreateProgram()
 	if p.native == 0 {
-		panic("glCreateProgram failed")
+		return errors.New("glCreateProgram failed")
 	}
 
 	for _, shaderId := range p.shaderIds {
@@ -38,13 +39,16 @@ func (p *program) create() {
 	}
 	p.native.Link()
 	if p.native.Get(gl.LINK_STATUS) == gl.FALSE {
-		panic("program error")
+		return errors.New("program error")
 	}
+	return nil
 }
 
-func initialize() {
+func initialize() error {
 	for _, shader := range shaders {
-		shader.compile()
+		if err := shader.compile(); err != nil {
+			return err
+		}
 	}
 	defer func() {
 		for _, shader := range shaders {
@@ -52,7 +56,7 @@ func initialize() {
 		}
 	}()
 
-	programColorMatrix.create()
+	return programColorMatrix.create()
 }
 
 func getAttributeLocation(program gl.Program, name string) gl.AttribLocation {

internal/opengl/internal/shader/shader.go

@@ -15,8 +15,9 @@
 package shader
 
 import (
+	"errors"
+	"fmt"
 	"github.com/go-gl/gl"
-	"log"
 )
 
 type shader struct {
@@ -75,26 +76,26 @@ void main(void) {
 	},
 }
 
-func (s *shader) compile() {
+func (s *shader) compile() error {
 	s.native = gl.CreateShader(s.shaderType)
 	if s.native == 0 {
-		panic("glCreateShader failed")
+		return errors.New("glCreateShader failed")
 	}
 
 	s.native.Source(s.source)
 	s.native.Compile()
 
 	if s.native.Get(gl.COMPILE_STATUS) == gl.FALSE {
-		s.showShaderLog()
+		return errors.New(fmt.Sprintf("shader compile failed: %s", s.shaderLog()))
-		panic("shader compile failed")
 	}
+	return nil
 }
 
-func (s *shader) showShaderLog() {
+func (s *shader) shaderLog() string {
 	if s.native.Get(gl.INFO_LOG_LENGTH) == 0 {
-		return
+		return ""
 	}
-	log.Fatalf("shader error: %s\n", s.native.GetInfoLog())
+	return s.native.GetInfoLog()
 }
 
 func (s *shader) delete() {

internal/opengl/texture.go

@@ -59,10 +59,10 @@ func (t *Texture) Size() (width, height int) {
 	return t.width, t.height
 }
 
-func createNativeTexture(textureWidth, textureHeight int, pixels []uint8, filter Filter) gl.Texture {
+func createNativeTexture(textureWidth, textureHeight int, pixels []uint8, filter Filter) (gl.Texture, error) {
 	nativeTexture := gl.GenTexture()
 	if nativeTexture < 0 {
-		panic("glGenTexture failed")
+		return 0, errors.New("glGenTexture failed")
 	}
 	gl.PixelStorei(gl.UNPACK_ALIGNMENT, 4)
 	nativeTexture.Bind(gl.TEXTURE_2D)
@@ -73,7 +73,7 @@ func createNativeTexture(textureWidth, textureHeight int, pixels []uint8, filter
 
 	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, textureWidth, textureHeight, 0, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
 
-	return nativeTexture
+	return nativeTexture, nil
 }
 
 func NewTexture(width, height int, filter Filter) (*Texture, error) {
@@ -85,7 +85,10 @@ func NewTexture(width, height int, filter Filter) (*Texture, error) {
 	if h < 4 {
 		return nil, errors.New("height must be equal or more than 4.")
 	}
-	native := createNativeTexture(w, h, nil, filter)
+	native, err := createNativeTexture(w, h, nil, filter)
+	if err != nil {
+		return nil, err
+	}
 	return &Texture{native, width, height}, nil
 }
 
@@ -99,7 +102,10 @@ func NewTextureFromImage(img image.Image, filter Filter) (*Texture, error) {
 	}
 	adjustedImage := adjustImageForTexture(img)
 	size := adjustedImage.Bounds().Size()
-	native := createNativeTexture(size.X, size.Y, adjustedImage.Pix, filter)
+	native, err := createNativeTexture(size.X, size.Y, adjustedImage.Pix, filter)
+	if err != nil {
+		return nil, err
+	}
 	return &Texture{native, origSize.X, origSize.Y}, nil
 }