go-opengl-pixel/batch.go

106 lines
2.8 KiB
Go

package pixel
import (
"image/color"
"github.com/go-gl/mathgl/mgl32"
)
// 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 TrianglesDrawer
fixpic *Picture
pic *Picture
mat mgl32.Mat3
col NRGBA
}
// NewBatch creates an empty Batch with the specified Picture and container.
//
// The container is where objects get accumulated. Batch will support precisely those vertex
// properties, that the supplied container supports.
//
// Note, that if the container does not support TrianglesColor, color masking will not work.
func NewBatch(pic *Picture, container Triangles) *Batch {
return &Batch{
cont: TrianglesDrawer{Triangles: container},
fixpic: pic,
}
}
// Clear removes all objects from the Batch.
func (b *Batch) Clear() {
b.cont.Update(&TrianglesData{})
}
// Draw draws all objects that are currently in the Batch onto another Target.
func (b *Batch) Draw(t Target) {
t.SetPicture(b.fixpic)
b.cont.Draw(t)
}
// MakeTriangles returns a specialized copy of the provided Triangles, that draws onto this Batch.
func (b *Batch) MakeTriangles(t Triangles) Triangles {
return &batchTriangles{
Triangles: t.Copy(),
trans: t.Copy(),
batch: b,
}
}
// SetPicture sets the current Picture that will be used with the following draws. The original
// Picture of this Picture (the one from which p was obtained by slicing) must be same as the
// original Picture of the Batch's Picture.
func (b *Batch) SetPicture(p *Picture) {
if p != nil && p.Texture() != b.fixpic.Texture() {
panic("batch: attempted to draw with a different underlying Picture")
}
b.pic = p
}
// SetTransform sets transforms used in the following draws onto the Batch.
func (b *Batch) SetTransform(t ...Transform) {
b.mat = transformToMat(t...)
}
// SetMaskColor sets a mask color used in the following draws onto the Batch.
func (b *Batch) SetMaskColor(c color.Color) {
if c == nil {
b.col = NRGBA{1, 1, 1, 1}
return
}
b.col = NRGBAModel.Convert(c).(NRGBA)
}
type batchTriangles struct {
Triangles
trans Triangles
data TrianglesData
batch *Batch
}
func (bt *batchTriangles) Draw() {
// need to apply transforms and mask color and picture bounds
bt.data.Update(bt.Triangles)
for i := range bt.data {
transPos := bt.batch.mat.Mul3x1(mgl32.Vec3{
float32(bt.data[i].Position.X()),
float32(bt.data[i].Position.Y()),
1,
})
bt.data[i].Position = V(float64(transPos.X()), float64(transPos.Y()))
bt.data[i].Color = bt.data[i].Color.Mul(bt.batch.col)
if bt.batch.pic != nil && bt.data[i].Texture != V(-1, -1) {
bt.data[i].Texture = pictureBounds(bt.batch.pic, bt.data[i].Texture)
}
}
bt.trans.Update(&bt.data)
bt.batch.cont.Append(bt.trans)
}