gpu: Merge GPU.Collect and GPU.Frame

There's no meaningful reason to have them separate. The intention was to
enable rendering concurrent with other processing, but that's gaining
framerate at the expense of input latency and complicating ImageOp
semantics.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

gpu/compute.go

@@ -559,7 +559,12 @@ func newShaders(ctx driver.Device, vsrc, fsrc shader.Sources) (vert driver.Verte
 	return
 }
 
-func (g *compute) Collect(viewport image.Point, ops *op.Ops) {
+func (g *compute) Frame(frameOps *op.Ops, target RenderTarget, viewport image.Point) error {
+	g.collect(viewport, frameOps)
+	return g.frame(target)
+}
+
+func (g *compute) collect(viewport image.Point, ops *op.Ops) {
 	g.viewport = viewport
 	g.collector.reset()
 	for i := range g.output.layerAtlases {
@@ -575,7 +580,7 @@ func (g *compute) Clear(col color.NRGBA) {
 	g.collector.clearColor = f32color.LinearFromSRGB(col)
 }
 
-func (g *compute) Frame(target RenderTarget) error {
+func (g *compute) frame(target RenderTarget) error {
 	viewport := g.viewport
 	defFBO := g.ctx.BeginFrame(target, g.collector.clear, viewport)
 	defer g.ctx.EndFrame()

gpu/gpu.go

@@ -43,12 +43,10 @@ type GPU interface {
 	Release()
 	// Clear sets the clear color for the next Frame.
 	Clear(color color.NRGBA)
-	// Collect the graphics operations from frame, given the viewport.
-	Collect(viewport image.Point, frame *op.Ops)
-	// Frame draws the collected operations to target.
-	Frame(target RenderTarget) error
+	// Frame draws the graphics operations from op into a viewport of target.
+	Frame(frame *op.Ops, target RenderTarget, viewport image.Point) error
 	// Profile returns the last available profiling information. Profiling
-	// information is requested when Collect sees an io/profile.Op, and the result
+	// information is requested when Frame sees an io/profile.Op, and the result
 	// is available through Profile at some later time.
 	Profile() string
 }
@@ -399,7 +397,12 @@ func (g *gpu) Release() {
 	g.ctx.Release()
 }
 
-func (g *gpu) Collect(viewport image.Point, frameOps *op.Ops) {
+func (g *gpu) Frame(frameOps *op.Ops, target RenderTarget, viewport image.Point) error {
+	g.collect(viewport, frameOps)
+	return g.frame(target)
+}
+
+func (g *gpu) collect(viewport image.Point, frameOps *op.Ops) {
 	g.renderer.blitter.viewport = viewport
 	g.renderer.pather.viewport = viewport
 	g.drawOps.reset(g.cache, viewport)
@@ -413,7 +416,7 @@ func (g *gpu) Collect(viewport image.Point, frameOps *op.Ops) {
 	}
 }
 
-func (g *gpu) Frame(target RenderTarget) error {
+func (g *gpu) frame(target RenderTarget) error {
 	viewport := g.renderer.blitter.viewport
 	defFBO := g.ctx.BeginFrame(target, g.drawOps.clear, viewport)
 	defer g.ctx.EndFrame()

gpu/headless/headless.go

@@ -109,8 +109,7 @@ func (w *Window) Release() {
 func (w *Window) Frame(frame *op.Ops) error {
 	return contextDo(w.ctx, func() error {
 		w.gpu.Clear(color.NRGBA{})
-		w.gpu.Collect(w.size, frame)
-		return w.gpu.Frame(driver.RenderTarget(w.fbo))
+		return w.gpu.Frame(frame, driver.RenderTarget(w.fbo), w.size)
 	})
 }