120 lines
3.1 KiB
Go
120 lines
3.1 KiB
Go
package pixel
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import "image/color"
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// Sprite is a drawable frame of a Picture. It's anchored by the center of it's Picture's frame.
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//
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// Frame specifies a rectangular portion of the Picture that will be drawn. For example, this
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// creates a Sprite that draws the whole Picture:
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//
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// sprite := pixel.NewSprite(pic, pic.Bounds())
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//
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// Note, that Sprite caches the results of MakePicture from Targets it's drawn to for each Picture
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// it's set to. What it means is that using a Sprite with an unbounded number of Pictures leads to a
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// memory leak, since Sprite caches them and never forgets. In such a situation, create a new Sprite
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// for each Picture.
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type Sprite struct {
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tri *TrianglesData
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frame Rect
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d Drawer
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matrix Matrix
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mask RGBA
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}
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// NewSprite creates a Sprite from the supplied frame of a Picture.
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func NewSprite(pic Picture, frame Rect) *Sprite {
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tri := MakeTrianglesData(6)
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s := &Sprite{
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tri: tri,
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d: Drawer{Triangles: tri, Cached: true},
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}
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s.matrix = IM
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s.mask = Alpha(1)
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s.Set(pic, frame)
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return s
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}
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// Set sets a new frame of a Picture for this Sprite.
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func (s *Sprite) Set(pic Picture, frame Rect) {
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s.d.Picture = pic
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if frame != s.frame {
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s.frame = frame
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s.calcData()
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}
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}
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// SetCached makes the sprite cache all the
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// incoming pictures if the argument is true, and
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// doesn't make it do that if the argument is false.
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func (s *Sprite) SetCached(cached bool) {
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s.d.Cached = cached
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}
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// Picture returns the current Sprite's Picture.
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func (s *Sprite) Picture() Picture {
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return s.d.Picture
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}
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// Frame returns the current Sprite's frame.
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func (s *Sprite) Frame() Rect {
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return s.frame
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}
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// Draw draws the Sprite onto the provided Target. The Sprite will be transformed by the given Matrix.
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//
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// This method is equivalent to calling DrawColorMask with nil color mask.
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func (s *Sprite) Draw(t Target, matrix Matrix) {
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s.DrawColorMask(t, matrix, nil)
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}
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// DrawColorMask draws the Sprite onto the provided Target. The Sprite will be transformed by the
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// given Matrix and all of it's color will be multiplied by the given mask.
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//
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// If the mask is nil, a fully opaque white mask will be used, which causes no effect.
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func (s *Sprite) DrawColorMask(t Target, matrix Matrix, mask color.Color) {
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dirty := false
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if matrix != s.matrix {
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s.matrix = matrix
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dirty = true
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}
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if mask == nil {
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mask = Alpha(1)
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}
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rgba := ToRGBA(mask)
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if rgba != s.mask {
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s.mask = rgba
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dirty = true
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}
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if dirty {
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s.calcData()
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}
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s.d.Draw(t)
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}
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func (s *Sprite) calcData() {
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var (
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center = s.frame.Center()
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horizontal = V(s.frame.W()/2, 0)
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vertical = V(0, s.frame.H()/2)
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)
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(*s.tri)[0].Position = Vec{}.Sub(horizontal).Sub(vertical)
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(*s.tri)[1].Position = Vec{}.Add(horizontal).Sub(vertical)
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(*s.tri)[2].Position = Vec{}.Add(horizontal).Add(vertical)
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(*s.tri)[3].Position = Vec{}.Sub(horizontal).Sub(vertical)
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(*s.tri)[4].Position = Vec{}.Add(horizontal).Add(vertical)
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(*s.tri)[5].Position = Vec{}.Sub(horizontal).Add(vertical)
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for i := range *s.tri {
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(*s.tri)[i].Color = s.mask
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(*s.tri)[i].Picture = center.Add((*s.tri)[i].Position)
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(*s.tri)[i].Intensity = 1
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(*s.tri)[i].Position = s.matrix.Project((*s.tri)[i].Position)
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}
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s.d.Dirty()
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}
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