gpu: remove compute renderer

The compute renderer is a failed experiment: a better port of the
Vello vector renderer exists[0] and the upcoming Go 1.24 release
no longer builds the gioui.org/cpu module because of #60725.

Remove it.

[0] https://github.com/dominikh/jello

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

gpu/cpu.go

@@ -1,129 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-package gpu
-
-import (
-	"unsafe"
-
-	"gioui.org/cpu"
-)
-
-// This file contains code specific to running compute shaders on the CPU.
-
-// dispatcher dispatches CPU compute programs across multiple goroutines.
-type dispatcher struct {
-	// done is notified when a worker completes its work slice.
-	done chan struct{}
-	// work receives work slice indices. It is closed when the dispatcher is released.
-	work chan work
-	// dispatch receives compute jobs, which is then split among workers.
-	dispatch chan dispatch
-	// sync receives notification when a Sync completes.
-	sync chan struct{}
-}
-
-type work struct {
-	ctx   *cpu.DispatchContext
-	index int
-}
-
-type dispatch struct {
-	_type   jobType
-	program *cpu.ProgramInfo
-	descSet unsafe.Pointer
-	x, y, z int
-}
-
-type jobType uint8
-
-const (
-	jobDispatch jobType = iota
-	jobBarrier
-	jobSync
-)
-
-func newDispatcher(workers int) *dispatcher {
-	d := &dispatcher{
-		work: make(chan work, workers),
-		done: make(chan struct{}, workers),
-		// Leave some room to avoid blocking calls to Dispatch.
-		dispatch: make(chan dispatch, 20),
-		sync:     make(chan struct{}),
-	}
-	for i := 0; i < workers; i++ {
-		go d.worker()
-	}
-	go d.dispatcher()
-	return d
-}
-
-func (d *dispatcher) dispatcher() {
-	defer close(d.work)
-	var free []*cpu.DispatchContext
-	defer func() {
-		for _, ctx := range free {
-			ctx.Free()
-		}
-	}()
-	var used []*cpu.DispatchContext
-	for job := range d.dispatch {
-		switch job._type {
-		case jobDispatch:
-			if len(free) == 0 {
-				free = append(free, cpu.NewDispatchContext())
-			}
-			ctx := free[len(free)-1]
-			free = free[:len(free)-1]
-			used = append(used, ctx)
-			ctx.Prepare(cap(d.work), job.program, job.descSet, job.x, job.y, job.z)
-			for i := 0; i < cap(d.work); i++ {
-				d.work <- work{
-					ctx:   ctx,
-					index: i,
-				}
-			}
-		case jobBarrier:
-			// Wait for all outstanding dispatches to complete.
-			for i := 0; i < len(used)*cap(d.work); i++ {
-				<-d.done
-			}
-			free = append(free, used...)
-			used = used[:0]
-		case jobSync:
-			d.sync <- struct{}{}
-		}
-	}
-}
-
-func (d *dispatcher) worker() {
-	thread := cpu.NewThreadContext()
-	defer thread.Free()
-	for w := range d.work {
-		w.ctx.Dispatch(w.index, thread)
-		d.done <- struct{}{}
-	}
-}
-
-func (d *dispatcher) Barrier() {
-	d.dispatch <- dispatch{_type: jobBarrier}
-}
-
-func (d *dispatcher) Sync() {
-	d.dispatch <- dispatch{_type: jobSync}
-	<-d.sync
-}
-
-func (d *dispatcher) Dispatch(program *cpu.ProgramInfo, descSet unsafe.Pointer, x, y, z int) {
-	d.dispatch <- dispatch{
-		_type:   jobDispatch,
-		program: program,
-		descSet: descSet,
-		x:       x,
-		y:       y,
-		z:       z,
-	}
-}
-
-func (d *dispatcher) Stop() {
-	close(d.dispatch)
-}

gpu/gpu.go

@@ -9,11 +9,11 @@ package gpu
 
 import (
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"image"
 	"image/color"
 	"math"
-	"os"
 	"reflect"
 	"time"
 	"unsafe"
@@ -343,13 +343,12 @@ func New(api API) (GPU, error) {
 func NewWithDevice(d driver.Device) (GPU, error) {
 	d.BeginFrame(nil, false, image.Point{})
 	defer d.EndFrame()
-	forceCompute := os.Getenv("GIORENDERER") == "forcecompute"
 	feats := d.Caps().Features
 	switch {
-	case !forceCompute && feats.Has(driver.FeatureFloatRenderTargets) && feats.Has(driver.FeatureSRGB):
+	case feats.Has(driver.FeatureFloatRenderTargets) && feats.Has(driver.FeatureSRGB):
 		return newGPU(d)
 	}
-	return newCompute(d)
+	return nil, errors.New("no available GPU driver")
 }
 
 func newGPU(ctx driver.Device) (*gpu, error) {
@@ -1484,7 +1483,7 @@ func (d *drawOps) buildVerts(pathData []byte, tr f32.Affine2D, outline bool, str
 // as needed and feeds them to the supplied splitter.
 func decodeToOutlineQuads(qs *quadSplitter, tr f32.Affine2D, pathData []byte) {
 	for len(pathData) >= scene.CommandSize+4 {
-		qs.contour = bo.Uint32(pathData)
+		qs.contour = binary.LittleEndian.Uint32(pathData)
 		cmd := ops.DecodeCommand(pathData[4:])
 		switch cmd.Op() {
 		case scene.OpLine:
@@ -1579,3 +1578,15 @@ func isPureOffset(t f32.Affine2D) bool {
 	a, b, _, d, e, _ := t.Elems()
 	return a == 1 && b == 0 && d == 0 && e == 1
 }
+
+func newShaders(ctx driver.Device, vsrc, fsrc shader.Sources) (vert driver.VertexShader, frag driver.FragmentShader, err error) {
+	vert, err = ctx.NewVertexShader(vsrc)
+	if err != nil {
+		return
+	}
+	frag, err = ctx.NewFragmentShader(fsrc)
+	if err != nil {
+		vert.Release()
+	}
+	return
+}