Remove panic

graphics.go

@@ -38,21 +38,21 @@ type TexturePart struct {
 
 // A Drawer is the interface that draws itself.
 type Drawer interface {
-	Draw(parts []TexturePart, geo GeometryMatrix, color ColorMatrix)
+	Draw(parts []TexturePart, geo GeometryMatrix, color ColorMatrix) error
 }
 
 // DrawWhole draws the whole texture.
-func DrawWhole(drawer Drawer, width, height int, geo GeometryMatrix, color ColorMatrix) {
+func DrawWhole(drawer Drawer, width, height int, geo GeometryMatrix, color ColorMatrix) error {
 	parts := []TexturePart{
 		{0, 0, Rect{0, 0, width, height}},
 	}
-	drawer.Draw(parts, geo, color)
+	return drawer.Draw(parts, geo, color)
 }
 
 // A Context is the interface that means a context of rendering.
 type GraphicsContext interface {
-	Clear()
+	Clear() error
-	Fill(r, g, b uint8)
+	Fill(r, g, b uint8) error
 	Texture(id TextureID) Drawer
 	RenderTarget(id RenderTargetID) Drawer
 	// TODO: ScreenRenderTarget() Drawer

graphicscontext.go

@@ -64,12 +64,12 @@ func (c *graphicsContext) dispose() {
 	idsInstance.deleteRenderTarget(c.screenID)
 }
 
-func (c *graphicsContext) Clear() {
+func (c *graphicsContext) Clear() error {
-	c.Fill(0, 0, 0)
+	return c.Fill(0, 0, 0)
 }
 
-func (c *graphicsContext) Fill(r, g, b uint8) {
+func (c *graphicsContext) Fill(r, g, b uint8) error {
-	idsInstance.fillRenderTarget(c.currentIDs[len(c.currentIDs)-1], r, g, b)
+	return idsInstance.fillRenderTarget(c.currentIDs[len(c.currentIDs)-1], r, g, b)
 }
 
 func (c *graphicsContext) Texture(id TextureID) Drawer {
@@ -112,7 +112,7 @@ type textureWithContext struct {
 	context *graphicsContext
 }
 
-func (t *textureWithContext) Draw(parts []TexturePart, geo GeometryMatrix, color ColorMatrix) {
+func (t *textureWithContext) Draw(parts []TexturePart, geo GeometryMatrix, color ColorMatrix) error {
 	currentID := t.context.currentIDs[len(t.context.currentIDs)-1]
-	idsInstance.drawTexture(currentID, t.id, parts, geo, color)
+	return idsInstance.drawTexture(currentID, t.id, parts, geo, color)
 }

ids.go

@@ -81,7 +81,10 @@ func (i *ids) createRenderTarget(width, height int, filter int) (RenderTargetID,
 
 	// The current binded framebuffer can be changed.
 	i.currentRenderTargetId = -1
-	r := opengl.NewRenderTargetFromTexture(texture)
+	r, err := opengl.NewRenderTargetFromTexture(texture)
+	if err != nil {
+		return 0, err
+	}
 
 	i.Lock()
 	defer i.Unlock()
@@ -124,26 +127,35 @@ func (i *ids) deleteRenderTarget(id RenderTargetID) {
 	delete(i.textures, textureId)
 }
 
-func (i *ids) fillRenderTarget(id RenderTargetID, r, g, b uint8) {
+func (i *ids) fillRenderTarget(id RenderTargetID, r, g, b uint8) error {
-	i.setViewportIfNeeded(id)
+	if err := i.setViewportIfNeeded(id); err != nil {
+		return err
+	}
 	const max = float64(math.MaxUint8)
 	gl.ClearColor(gl.GLclampf(float64(r)/max), gl.GLclampf(float64(g)/max), gl.GLclampf(float64(b)/max), 1)
 	gl.Clear(gl.COLOR_BUFFER_BIT)
+	return nil
 }
 
-func (i *ids) drawTexture(target RenderTargetID, id TextureID, parts []TexturePart, geo GeometryMatrix, color ColorMatrix) {
+func (i *ids) drawTexture(target RenderTargetID, id TextureID, parts []TexturePart, geo GeometryMatrix, color ColorMatrix) error {
 	texture := i.textureAt(id)
-	i.setViewportIfNeeded(target)
+	if err := i.setViewportIfNeeded(target); err != nil {
+		return err
+	}
 	r := i.renderTargetAt(target)
 	projectionMatrix := r.ProjectionMatrix()
 	quads := textureQuads(parts, texture.Width(), texture.Height())
 	shader.DrawTexture(texture.Native(), projectionMatrix, quads, &geo, &color)
+	return nil
 }
 
-func (i *ids) setViewportIfNeeded(id RenderTargetID) {
+func (i *ids) setViewportIfNeeded(id RenderTargetID) error {
 	r := i.renderTargetAt(id)
 	if i.currentRenderTargetId != id {
-		r.SetAsViewport()
+		if err := r.SetAsViewport(); err != nil {
+			return err
+		}
 		i.currentRenderTargetId = id
 	}
+	return nil
 }

internal/opengl/rendertarget.go

@@ -17,6 +17,7 @@ limitations under the License.
 package opengl
 
 import (
+	"errors"
 	"fmt"
 	"github.com/go-gl/gl"
 )
@@ -50,13 +51,16 @@ func NewRenderTarget(width, height int, flipY bool) *RenderTarget {
 	}
 }
 
-func NewRenderTargetFromTexture(texture *Texture) *RenderTarget {
+func NewRenderTargetFromTexture(texture *Texture) (*RenderTarget, error) {
-	framebuffer := createFramebuffer(texture.Native())
+	framebuffer, err := createFramebuffer(texture.Native())
+	if err != nil {
+		return nil, err
+	}
 	return &RenderTarget{
 		framebuffer: framebuffer,
 		width:       texture.Width(),
 		height:      texture.Height(),
-	}
+	}, nil
 }
 
 func (r *RenderTarget) Width() int {
@@ -75,13 +79,13 @@ func (r *RenderTarget) Dispose() {
 	r.framebuffer.Delete()
 }
 
-func createFramebuffer(nativeTexture gl.Texture) gl.Framebuffer {
+func createFramebuffer(nativeTexture gl.Texture) (gl.Framebuffer, error) {
 	framebuffer := gl.GenFramebuffer()
 	framebuffer.Bind()
 
 	gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, nativeTexture, 0)
 	if gl.CheckFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE {
-		panic("creating framebuffer failed")
+		return 0, errors.New("creating framebuffer failed")
 	}
 
 	// Set this framebuffer opaque because alpha values on a target might be
@@ -89,15 +93,15 @@ func createFramebuffer(nativeTexture gl.Texture) gl.Framebuffer {
 	gl.ClearColor(0, 0, 0, 1)
 	gl.Clear(gl.COLOR_BUFFER_BIT)
 
-	return framebuffer
+	return framebuffer, nil
 }
 
-func (r *RenderTarget) SetAsViewport() {
+func (r *RenderTarget) SetAsViewport() error {
 	gl.Flush()
 	r.framebuffer.Bind()
 	err := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
 	if err != gl.FRAMEBUFFER_COMPLETE {
-		panic(fmt.Sprintf("glBindFramebuffer failed: %d", err))
+		return errors.New(fmt.Sprintf("glBindFramebuffer failed: %d", err))
 	}
 
 	gl.BlendFuncSeparate(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA, gl.ZERO, gl.ONE)
@@ -105,6 +109,7 @@ func (r *RenderTarget) SetAsViewport() {
 	width := AdjustSizeForTexture(r.width)
 	height := AdjustSizeForTexture(r.height)
 	gl.Viewport(0, 0, width, height)
+	return nil
 }
 
 func (r *RenderTarget) ProjectionMatrix() [4][4]float64 {

syncgraphicscontext.go

@@ -27,16 +27,18 @@ type syncGraphicsContext struct {
 
 var _ GraphicsContext = new(syncGraphicsContext)
 
-func (c *syncGraphicsContext) Clear() {
+func (c *syncGraphicsContext) Clear() (err error) {
 	c.syncer.Sync(func() {
-		c.innerGraphicsContext.Clear()
+		err = c.innerGraphicsContext.Clear()
 	})
+	return
 }
 
-func (c *syncGraphicsContext) Fill(r, g, b uint8) {
+func (c *syncGraphicsContext) Fill(r, g, b uint8) (err error) {
 	c.syncer.Sync(func() {
-		c.innerGraphicsContext.Fill(r, g, b)
+		err = c.innerGraphicsContext.Fill(r, g, b)
 	})
+	return
 }
 
 func (c *syncGraphicsContext) Texture(id TextureID) (d Drawer) {
@@ -78,8 +80,9 @@ type drawer struct {
 
 var _ Drawer = new(drawer)
 
-func (d *drawer) Draw(parts []TexturePart, geo GeometryMatrix, color ColorMatrix) {
+func (d *drawer) Draw(parts []TexturePart, geo GeometryMatrix, color ColorMatrix) (err error) {
 	d.syncer.Sync(func() {
-		d.innerDrawer.Draw(parts, geo, color)
+		err = d.innerDrawer.Draw(parts, geo, color)
 	})
+	return
 }