go-opengl-pixel/batch.go

180 lines
4.2 KiB
Go

package pixel
import (
"fmt"
"image/color"
)
// Batch is a Target that allows for efficient drawing of many objects with the same Picture (but
// different slices of the same Picture are allowed).
//
// To put an object into a Batch, just draw it onto it:
// object.Draw(batch)
type Batch struct {
cont Drawer
mat Matrix
col NRGBA
}
var _ BasicTarget = (*Batch)(nil)
// NewBatch creates an empty Batch with the specified Picture and container.
//
// The container is where objects get accumulated. Batch will support precisely those Triangles
// properties, that the supplied container supports. If you retain access to the container and
// change it, call Dirty to notify Batch about the change.
//
// Note, that if the container does not support TrianglesColor, color masking will not work.
func NewBatch(container Triangles, pic Picture) *Batch {
b := &Batch{cont: Drawer{Triangles: container, Picture: pic}}
b.SetMatrix(IM)
b.SetColorMask(NRGBA{1, 1, 1, 1})
return b
}
// Dirty notifies Batch about an external modification of it's container. If you retain access to
// the Batch's container and change it, call Dirty to notify Batch about the change.
//
// container := &pixel.TrianglesData{}
// batch := pixel.NewBatch(container, nil)
// container.SetLen(10) // container changed from outside of Batch
// batch.Dirty() // notify Batch about the change
func (b *Batch) Dirty() {
b.cont.Dirty()
}
// Clear removes all objects from the Batch.
func (b *Batch) Clear() {
b.cont.Triangles.SetLen(0)
b.cont.Dirty()
}
// Draw draws all objects that are currently in the Batch onto another Target.
func (b *Batch) Draw(t Target) {
b.cont.Draw(t)
}
// SetMatrix sets a Matrix that every point will be projected by.
func (b *Batch) SetMatrix(m Matrix) {
b.mat = m
}
// SetColorMask sets a mask color used in the following draws onto the Batch.
func (b *Batch) SetColorMask(c color.Color) {
if c == nil {
b.col = NRGBA{1, 1, 1, 1}
return
}
b.col = NRGBAModel.Convert(c).(NRGBA)
}
// MakeTriangles returns a specialized copy of the provided Triangles that draws onto this Batch.
func (b *Batch) MakeTriangles(t Triangles) TargetTriangles {
bt := &batchTriangles{
tri: t.Copy(),
tmp: MakeTrianglesData(t.Len()),
dst: b,
}
return bt
}
// MakePicture returns a specialized copy of the provided Picture that draws onto this Batch.
func (b *Batch) MakePicture(p Picture) TargetPicture {
if p.Original() != b.cont.Picture.Original() {
panic(fmt.Errorf("(%T).MakePicture: Picture is not a slice of Batch's Picture", b))
}
bp := &batchPicture{
pic: p,
dst: b,
}
bp.orig = bp
return bp
}
type batchTriangles struct {
tri Triangles
tmp *TrianglesData
dst *Batch
}
func (bt *batchTriangles) Len() int {
return bt.tri.Len()
}
func (bt *batchTriangles) SetLen(len int) {
bt.tri.SetLen(len)
bt.tmp.SetLen(len)
}
func (bt *batchTriangles) Slice(i, j int) Triangles {
return &batchTriangles{
tri: bt.tri.Slice(i, j),
tmp: bt.tmp.Slice(i, j).(*TrianglesData),
dst: bt.dst,
}
}
func (bt *batchTriangles) Update(t Triangles) {
bt.tri.Update(t)
}
func (bt *batchTriangles) Copy() Triangles {
return &batchTriangles{
tri: bt.tri.Copy(),
tmp: bt.tmp.Copy().(*TrianglesData),
dst: bt.dst,
}
}
func (bt *batchTriangles) draw(bp *batchPicture) {
bt.tmp.Update(bt.tri)
for i := range *bt.tmp {
(*bt.tmp)[i].Position = bt.dst.mat.Project((*bt.tmp)[i].Position)
(*bt.tmp)[i].Color = bt.dst.col.Mul((*bt.tmp)[i].Color)
}
cont := bt.dst.cont.Triangles
cont.SetLen(cont.Len() + bt.tri.Len())
added := cont.Slice(cont.Len()-bt.tri.Len(), cont.Len())
added.Update(bt.tri)
added.Update(bt.tmp)
bt.dst.cont.Dirty()
}
func (bt *batchTriangles) Draw() {
bt.draw(nil)
}
type batchPicture struct {
pic Picture
orig *batchPicture
dst *Batch
}
func (bp *batchPicture) Bounds() Rect {
return bp.pic.Bounds()
}
func (bp *batchPicture) Slice(r Rect) Picture {
return &batchPicture{
pic: bp.pic.Slice(r),
orig: bp.orig,
dst: bp.dst,
}
}
func (bp *batchPicture) Original() Picture {
return bp.orig
}
func (bp *batchPicture) Draw(t TargetTriangles) {
bt := t.(*batchTriangles)
if bp.dst != bt.dst {
panic(fmt.Errorf("(%T).Draw: TargetTriangles generated by different Batch", bp))
}
bt.draw(bp)
}