Add comments (to pass golint)

colormatrix.go

@@ -21,12 +21,15 @@ import (
 	"math"
 )
 
+// ColorMatrixDim is a dimension of a ColorMatrix.
 const ColorMatrixDim = 5
 
+// A ColorMatrix represents a matrix to transform coloring when rendering a texture or a render target.
 type ColorMatrix struct {
 	Elements [ColorMatrixDim - 1][ColorMatrixDim]float64
 }
 
+// ColorMatrixI returns an identity color matrix.
 func ColorMatrixI() ColorMatrix {
 	return ColorMatrix{
 		[ColorMatrixDim - 1][ColorMatrixDim]float64{
@@ -42,16 +45,19 @@ func (c *ColorMatrix) dim() int {
 	return ColorMatrixDim
 }
 
+// Element returns a value of a matrix at (i, j).
 func (c *ColorMatrix) Element(i, j int) float64 {
 	return c.Elements[i][j]
 }
 
+// Concat multiplies a color matrix with the other color matrix.
 func (c *ColorMatrix) Concat(other ColorMatrix) {
 	result := ColorMatrix{}
 	mul(&other, c, &result)
 	*c = result
 }
 
+// IsIdentity returns a boolean indicating whether the color matrix is an identity.
 func (c *ColorMatrix) IsIdentity() bool {
 	return isIdentity(c)
 }
@@ -60,6 +66,7 @@ func (c *ColorMatrix) setElement(i, j int, element float64) {
 	c.Elements[i][j] = element
 }
 
+// Monochrome returns a color matrix to make the texture monochrome.
 func Monochrome() ColorMatrix {
 	const r float64 = 6968.0 / 32768.0
 	const g float64 = 23434.0 / 32768.0
@@ -83,6 +90,7 @@ func rgba(clr color.Color) (float64, float64, float64, float64) {
 	return rf, gf, bf, af
 }
 
+// Scale scales the color matrix by clr.
 func (c *ColorMatrix) Scale(clr color.Color) {
 	rf, gf, bf, af := rgba(clr)
 	for i, e := range []float64{rf, gf, bf, af} {
@@ -92,6 +100,7 @@ func (c *ColorMatrix) Scale(clr color.Color) {
 	}
 }
 
+// Translate translates the color matrix by clr.
 func (c *ColorMatrix) Translate(clr color.Color) {
 	rf, gf, bf, af := rgba(clr)
 	c.Elements[0][4] = rf

gamecontext.go

@@ -21,14 +21,17 @@ import (
 	"image"
 )
 
+// IsKeyPressed returns a boolean indicating whether key is pressed.
 func IsKeyPressed(key Key) bool {
 	return currentUI.input.isKeyPressed(key)
 }
 
+// CursorPosition returns a position of a mouse cursor.
 func CursorPosition() (x, y int) {
 	return currentUI.input.cursorPosition()
 }
 
+// IsMouseButtonPressed returns a boolean indicating whether mouseButton is pressed.
 func IsMouseButtonPressed(mouseButton MouseButton) bool {
 	return currentUI.input.isMouseButtonPressed(mouseButton)
 }
@@ -44,10 +47,12 @@ func glFilter(f Filter) int {
 	}
 }
 
+// NewRenderTargetID returns a new RenderTargetID.
 func NewRenderTargetID(width, height int, filter Filter) (RenderTargetID, error) {
 	return currentUI.newRenderTargetID(width, height, glFilter(filter))
 }
 
+// NewTextureID returns a new TextureID.
 func NewTextureID(img image.Image, filter Filter) (TextureID, error) {
 	return currentUI.newTextureID(img, glFilter(filter))
 }

geometrymatrix.go

@@ -20,12 +20,15 @@ import (
 	"math"
 )
 
+// GeometryMatrixDim is a dimension of a GeometryMatrix.
 const GeometryMatrixDim = 3
 
+// A GeometryMatrix represents a matrix to transform geometry when rendering a texture or a render target.
 type GeometryMatrix struct {
 	Elements [GeometryMatrixDim - 1][GeometryMatrixDim]float64
 }
 
+// GeometryMatrixI returns an identity geometry matrix.
 func GeometryMatrixI() GeometryMatrix {
 	return GeometryMatrix{
 		[GeometryMatrixDim - 1][GeometryMatrixDim]float64{
@@ -39,16 +42,19 @@ func (g *GeometryMatrix) dim() int {
 	return GeometryMatrixDim
 }
 
+// Element returns a value of a matrix at (i, j).
 func (g *GeometryMatrix) Element(i, j int) float64 {
 	return g.Elements[i][j]
 }
 
+// Concat multiplies a geometry matrix with the other geometry matrix.
 func (g *GeometryMatrix) Concat(other GeometryMatrix) {
 	result := GeometryMatrix{}
 	mul(&other, g, &result)
 	*g = result
 }
 
+// IsIdentity returns a boolean indicating whether the geometry matrix is an identity.
 func (g *GeometryMatrix) IsIdentity() bool {
 	return isIdentity(g)
 }
@@ -57,11 +63,13 @@ func (g *GeometryMatrix) setElement(i, j int, element float64) {
 	g.Elements[i][j] = element
 }
 
+// Translate translates the geometry matrix by (tx, ty).
 func (g *GeometryMatrix) Translate(tx, ty float64) {
 	g.Elements[0][2] += tx
 	g.Elements[1][2] += ty
 }
 
+// Scale scales the geometry matrix by (x, y).
 func (g *GeometryMatrix) Scale(x, y float64) {
 	g.Elements[0][0] *= x
 	g.Elements[0][1] *= x
@@ -71,6 +79,7 @@ func (g *GeometryMatrix) Scale(x, y float64) {
 	g.Elements[1][2] *= y
 }
 
+// Rotate rotates the geometry matrix by theta.
 func (g *GeometryMatrix) Rotate(theta float64) {
 	sin, cos := math.Sincos(theta)
 	rotate := GeometryMatrix{

graphics.go

@@ -49,7 +49,7 @@ func DrawWhole(drawer Drawer, width, height int, geo GeometryMatrix, color Color
 	return drawer.Draw(parts, geo, color)
 }
 
-// A Context is the interface that means a context of rendering.
+// A GraphicsContext is the interface that means a context of rendering.
 type GraphicsContext interface {
 	Clear() error
 	Fill(r, g, b uint8) error
@@ -64,6 +64,7 @@ type GraphicsContext interface {
 // target is maginified or minified.
 type Filter int
 
+// Filters
 const (
 	FilterNearest Filter = iota
 	FilterLinear

ids.go

@@ -29,8 +29,8 @@ type ids struct {
 	textures              map[TextureID]*opengl.Texture
 	renderTargets         map[RenderTargetID]*opengl.RenderTarget
 	renderTargetToTexture map[RenderTargetID]TextureID
-	lastId                int
-	currentRenderTargetId RenderTargetID
+	lastID                int
+	currentRenderTargetID RenderTargetID
 	sync.RWMutex
 }
 
@@ -38,7 +38,7 @@ var idsInstance = &ids{
 	textures:              map[TextureID]*opengl.Texture{},
 	renderTargets:         map[RenderTargetID]*opengl.RenderTarget{},
 	renderTargetToTexture: map[RenderTargetID]TextureID{},
-	currentRenderTargetId: -1,
+	currentRenderTargetID: -1,
 }
 
 func (i *ids) textureAt(id TextureID) *opengl.Texture {
@@ -67,10 +67,10 @@ func (i *ids) createTexture(img image.Image, filter int) (TextureID, error) {
 
 	i.Lock()
 	defer i.Unlock()
-	i.lastId++
-	textureId := TextureID(i.lastId)
-	i.textures[textureId] = texture
-	return textureId, nil
+	i.lastID++
+	textureID := TextureID(i.lastID)
+	i.textures[textureID] = texture
+	return textureID, nil
 }
 
 func (i *ids) createRenderTarget(width, height int, filter int) (RenderTargetID, error) {
@@ -80,7 +80,7 @@ func (i *ids) createRenderTarget(width, height int, filter int) (RenderTargetID,
 	}
 
 	// The current binded framebuffer can be changed.
-	i.currentRenderTargetId = -1
+	i.currentRenderTargetID = -1
 	r, err := opengl.NewRenderTargetFromTexture(texture)
 	if err != nil {
 		return 0, err
@@ -88,24 +88,24 @@ func (i *ids) createRenderTarget(width, height int, filter int) (RenderTargetID,
 
 	i.Lock()
 	defer i.Unlock()
-	i.lastId++
-	textureId := TextureID(i.lastId)
-	i.lastId++
-	renderTargetId := RenderTargetID(i.lastId)
+	i.lastID++
+	textureID := TextureID(i.lastID)
+	i.lastID++
+	renderTargetID := RenderTargetID(i.lastID)
 
-	i.textures[textureId] = texture
-	i.renderTargets[renderTargetId] = r
-	i.renderTargetToTexture[renderTargetId] = textureId
+	i.textures[textureID] = texture
+	i.renderTargets[renderTargetID] = r
+	i.renderTargetToTexture[renderTargetID] = textureID
 
-	return renderTargetId, nil
+	return renderTargetID, nil
 }
 
 // NOTE: renderTarget can't be used as a texture.
 func (i *ids) addRenderTarget(renderTarget *opengl.RenderTarget) RenderTargetID {
 	i.Lock()
 	defer i.Unlock()
-	i.lastId++
-	id := RenderTargetID(i.lastId)
+	i.lastID++
+	id := RenderTargetID(i.lastID)
 	i.renderTargets[id] = renderTarget
 
 	return id
@@ -116,15 +116,15 @@ func (i *ids) deleteRenderTarget(id RenderTargetID) {
 	defer i.Unlock()
 
 	renderTarget := i.renderTargets[id]
-	textureId := i.renderTargetToTexture[id]
-	texture := i.textures[textureId]
+	textureID := i.renderTargetToTexture[id]
+	texture := i.textures[textureID]
 
 	renderTarget.Dispose()
 	texture.Dispose()
 
 	delete(i.renderTargets, id)
 	delete(i.renderTargetToTexture, id)
-	delete(i.textures, textureId)
+	delete(i.textures, textureID)
 }
 
 func (i *ids) fillRenderTarget(id RenderTargetID, r, g, b uint8) error {
@@ -151,11 +151,11 @@ func (i *ids) drawTexture(target RenderTargetID, id TextureID, parts []TexturePa
 
 func (i *ids) setViewportIfNeeded(id RenderTargetID) error {
 	r := i.renderTargetAt(id)
-	if i.currentRenderTargetId != id {
+	if i.currentRenderTargetID != id {
 		if err := r.SetAsViewport(); err != nil {
 			return err
 		}
-		i.currentRenderTargetId = id
+		i.currentRenderTargetID = id
 	}
 	return nil
 }

keys.go

@@ -16,9 +16,12 @@ limitations under the License.
 
 package ebiten
 
+// A Key represents a keyboard key.
 type Key int
 
 // TODO: Add more keys.
+
+// Keys
 const (
 	KeyUp Key = iota
 	KeyDown
@@ -28,8 +31,10 @@ const (
 	KeyMax
 )
 
+// A MouseButton represents a mouse button.
 type MouseButton int
 
+// MouseButtons
 const (
 	MouseButtonLeft MouseButton = iota
 	MouseButtonRight

run.go

@@ -23,6 +23,7 @@ import (
 	"time"
 )
 
+// A Game is the interface that represents a game.
 type Game interface {
 	Update() error
 	Draw(gr GraphicsContext) error