func (e *engine) render(n *sprite.Node, t clock.Time) {
if n.EngineFields.Index == 0 {
panic("portable: sprite.Node not registered")
}
if n.Arranger != nil {
n.Arranger.Arrange(e, n, t)
}
// Push absTransforms.
// TODO: cache absolute transforms and use EngineFields.Dirty?
rel := &e.nodes[n.EngineFields.Index].relTransform
m := f32.Affine{}
m.Mul(&e.absTransforms[len(e.absTransforms)-1], rel)
e.absTransforms = append(e.absTransforms, m)
if x := n.EngineFields.SubTex; x.T != nil {
// Affine transforms work in geom.Pt, which is entirely
// independent of the number of pixels in a texture. A texture
// of any image.Rectangle bounds rendered with
//
// Affine{{1, 0, 0}, {0, 1, 0}}
//
// should have the dimensions (1pt, 1pt). To do this we divide
// by the pixel width and height, reducing the texture to
// (1px, 1px) of the destination image. Multiplying by
// sz.PixelsPerPt, done in Render above, makes it (1pt, 1pt).
dx, dy := x.R.Dx(), x.R.Dy()
if dx > 0 && dy > 0 {
m.Scale(&m, 1/float32(dx), 1/float32(dy))
// TODO(nigeltao): delete the double-inverse: one here and one
// inside func affine.
m.Inverse(&m) // See the documentation on the affine function.
affine(e.dst, x.T.(*texture).m, x.R, nil, &m, draw.Over)
}
}
for c := n.FirstChild; c != nil; c = c.NextSibling {
e.render(c, t)
}
// Pop absTransforms.
e.absTransforms = e.absTransforms[:len(e.absTransforms)-1]
}
func (e *engine) render(n *sprite.Node, t clock.Time, sz size.Event) {
if n.EngineFields.Index == 0 {
panic("glsprite: sprite.Node not registered")
}
if n.Arranger != nil {
n.Arranger.Arrange(e, n, t)
}
// Push absTransforms.
// TODO: cache absolute transforms and use EngineFields.Dirty?
rel := &e.nodes[n.EngineFields.Index].relTransform
m := f32.Affine{}
m.Mul(&e.absTransforms[len(e.absTransforms)-1], rel)
e.absTransforms = append(e.absTransforms, m)
if x := n.EngineFields.SubTex; x.T != nil {
x.T.(*texture).glImage.Draw(
sz,
geom.Point{
geom.Pt(m[0][2]),
geom.Pt(m[1][2]),
},
geom.Point{
geom.Pt(m[0][2] + m[0][0]),
geom.Pt(m[1][2] + m[1][0]),
},
geom.Point{
geom.Pt(m[0][2] + m[0][1]),
geom.Pt(m[1][2] + m[1][1]),
},
x.R,
)
}
for c := n.FirstChild; c != nil; c = c.NextSibling {
e.render(c, t, sz)
}
// Pop absTransforms.
e.absTransforms = e.absTransforms[:len(e.absTransforms)-1]
}