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gpu: [compute] clip transformed images to their bounds

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A follow-up change will cause some transformed images to render outside
their allocated atlas bounds. This change uses the GPU viewport to clip
them so they won't overwrite other atlas content.

Updates gio#219

Signed-off-by: Elias Naur <mail@eliasnaur.com>
This commit is contained in:
Elias Naur
2021-08-27 08:39:35 +02:00
parent 6818af9390
commit 9e9cb17a5d
1 changed files with 19 additions and 11 deletions
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gpu/compute.go
+19 -11
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@@ -917,6 +917,10 @@ func (g *compute) renderMaterials() error {
atlas *textureAtlas
imgAtlas *textureAtlas
)
// A material is clipped to avoid drawing outside its atlas bounds.
// However, imprecision in the clipping may cause a single pixel
// overflow.
var padding = image.Pt(1, 1)
var allocStart int
for len(texOps) > 0 {
op := &texOps[0]
@@ -933,13 +937,10 @@ func (g *compute) renderMaterials() error {
}
imgAtlas = op.imgAlloc.atlas
quad, bounds := g.materialQuad(imgAtlas.size, op.key.transform, op.img, op.imgAlloc.rect.Min)
// A material is clipped to avoid drawing outside its atlas bounds.
// However, imprecision in the clipping may cause a single pixel
// overflow. Be safe.
size := bounds.Size().Add(image.Pt(1, 1))
size := bounds.Size()
alloc, fits := g.atlasAlloc(allocQuery{
atlas: atlas,
size: size,
size: size.Add(padding),
format: driver.TextureFormatRGBA8,
bindings: combinedBindings,
})
@@ -951,11 +952,15 @@ func (g *compute) renderMaterials() error {
}
atlas = alloc.atlas
alloc.cpu = g.useCPU
// Position quad to match place.
offsetf := layout.FPt(alloc.rect.Min.Sub(bounds.Min))
offsetf := layout.FPt(bounds.Min.Mul(-1))
scale := f32.Pt(float32(size.X), float32(size.Y))
for i := range quad {
// Position quad to match place.
quad[i].posX += offsetf.X
quad[i].posY += offsetf.Y
// Scale to match viewport [0, 1].
quad[i].posX /= scale.X
quad[i].posY /= scale.Y
}
// Draw quad as two triangles.
m.quads = append(m.quads, quad[0], quad[1], quad[3], quad[3], quad[1], quad[2])
@@ -980,7 +985,7 @@ func (g *compute) renderMaterials() error {
}
// Transform to clip space: [-1, -1] - [1, 1] and flip Y-axis to cancel the implied transformation
// between framebuffer and texture space.
m.vert.uniforms.scale = [2]float32{2 / float32(atlas.size.X), -2 / float32(atlas.size.Y)}
m.vert.uniforms.scale = [2]float32{2, -2}
m.vert.uniforms.pos = [2]float32{-1, +1}
m.vert.buf.Upload(byteslice.Struct(m.vert.uniforms))
g.ctx.BindVertexUniforms(m.vert.buf)
@@ -995,16 +1000,19 @@ func (g *compute) renderMaterials() error {
d.Action = driver.LoadActionClear
}
g.ctx.BindFramebuffer(atlas.fbo, d)
g.ctx.Viewport(0, 0, atlas.size.X, atlas.size.Y)
g.ctx.BindPipeline(m.pipeline)
g.ctx.BindVertexBuffer(m.buffer.buffer, 0)
g.ctx.DrawArrays(driver.DrawModeTriangles, 0, len(m.quads))
newAllocs := atlas.allocs[allocStart:]
for i, a := range newAllocs {
sz := a.rect.Size().Sub(padding)
g.ctx.Viewport(a.rect.Min.X, a.rect.Min.Y, sz.X, sz.Y)
g.ctx.DrawArrays(driver.DrawModeTriangles, i*6, 6)
}
if !g.useCPU {
continue
}
copyFBO := atlas.fbo
data := atlas.cpuImage.Data()
newAllocs := atlas.allocs[allocStart:]
for _, a := range newAllocs {
stride := atlas.size.X * 4
col := a.rect.Min.X * 4