1//go:build linux
2
3package vkdevice
4
5import (
6 "fmt"
7 "image"
8 "math"
9 "unsafe"
10
11 "github.com/bnema/purego-vulkan/vulkan"
12)
13
14// Readback is only allocated when NEFERGUI_DEBUG_DIR is set. Its transfer copy is
15// recorded after drawing and before the acquire semaphore signals; mapping
16// waits for the submission fence, never for compositor release.
17type Readback struct {
18 device *Device
19 Buffer vulkan.Buffer
20 Memory vulkan.DeviceMemory
21 width, height int32
22}
23
24func (d *Device) NewReadback(width, height int32) (r *Readback, err error) {
25 if width <= 0 || height <= 0 || uint64(width)*uint64(height) > math.MaxInt/4 {
26 return nil, fmt.Errorf("invalid readback dimensions %dx%d", width, height)
27 }
28 r = &Readback{device: d, width: width, height: height}
29 defer func() {
30 if err != nil {
31 r.Close()
32 }
33 }()
34 ci := vulkan.BufferCreateInfo{SType: vulkan.StructureTypeBufferCreateInfo, Size: vulkan.DeviceSize(width) * vulkan.DeviceSize(height) * 4, Usage: vulkan.BufferUsageTransferDstBit, SharingMode: vulkan.SharingModeExclusive}
35 if err = vulkan.Check(d.Dispatch.CreateBuffer(d.Logical, &ci, nil, &r.Buffer)); err != nil {
36 return nil, err
37 }
38 var req vulkan.MemoryRequirements
39 d.Dispatch.GetBufferMemoryRequirements(d.Logical, r.Buffer, &req)
40 var memory vulkan.PhysicalDeviceMemoryProperties
41 d.InstanceDispatch.GetPhysicalDeviceMemoryProperties(d.Physical, &memory)
42 // Prefer host-cached memory: CPU reads from uncached (write-combined)
43 // memory are orders of magnitude slower for window-sized images.
44 index := uint32(math.MaxUint32)
45 coherent := vulkan.MemoryPropertyFlags(vulkan.MemoryPropertyHostVisibleBit | vulkan.MemoryPropertyHostCoherentBit)
46 for _, want := range []vulkan.MemoryPropertyFlags{coherent | vulkan.MemoryPropertyHostCachedBit, coherent} {
47 for i := uint32(0); i < memory.MemoryTypeCount && index == math.MaxUint32; i++ {
48 if req.MemoryTypeBits&(1<<i) != 0 && memory.MemoryTypes[i].PropertyFlags&want == want {
49 index = i
50 }
51 }
52 }
53 if index == math.MaxUint32 {
54 return nil, fmt.Errorf("no host-coherent readback memory type")
55 }
56 allocate := vulkan.MemoryAllocateInfo{SType: vulkan.StructureTypeMemoryAllocateInfo, AllocationSize: req.Size, MemoryTypeIndex: index}
57 if err = vulkan.Check(d.Dispatch.AllocateMemory(d.Logical, &allocate, nil, &r.Memory)); err != nil {
58 return nil, err
59 }
60 if err = vulkan.Check(d.Dispatch.BindBufferMemory(d.Logical, r.Buffer, r.Memory, 0)); err != nil {
61 return nil, err
62 }
63 return r, nil
64}
65func (r *Readback) record(cmd vulkan.CommandBuffer, img vulkan.Image) {
66 copy := vulkan.BufferImageCopy{ImageSubresource: vulkan.ImageSubresourceLayers{AspectMask: vulkan.ImageAspectColorBit, LayerCount: 1}, ImageExtent: vulkan.Extent3D{Width: uint32(r.width), Height: uint32(r.height), Depth: 1}}
67 r.device.Dispatch.CmdCopyImageToBuffer(cmd, img, vulkan.ImageLayoutTransferSrcOptimal, r.Buffer, 1, ©)
68}
69
70// Copy returns the completed readback as an owned image whose pixels are still
71// in B8G8R8A8 order. It performs one bulk copy; call SwizzleBGRA off the state
72// owner before encoding.
73func (r *Readback) Copy() (*image.NRGBA, error) {
74 var ptr unsafe.Pointer
75 size := vulkan.DeviceSize(r.width) * vulkan.DeviceSize(r.height) * 4
76 if err := vulkan.Check(r.device.Dispatch.MapMemory(r.device.Logical, r.Memory, 0, size, 0, &ptr)); err != nil {
77 return nil, err
78 }
79 defer r.device.Dispatch.UnmapMemory(r.device.Logical, r.Memory)
80 out := image.NewNRGBA(image.Rect(0, 0, int(r.width), int(r.height)))
81 copy(out.Pix, unsafe.Slice((*byte)(ptr), int(size)))
82 return out, nil
83}
84
85// SwizzleBGRA converts B8G8R8A8 pixels to RGBA in place.
86func SwizzleBGRA(img *image.NRGBA) {
87 p := img.Pix
88 for i := 0; i+3 < len(p); i += 4 {
89 p[i], p[i+2] = p[i+2], p[i]
90 }
91}
92func (r *Readback) Close() {
93 if r == nil || r.device == nil {
94 return
95 }
96 if r.Buffer != 0 {
97 r.device.Dispatch.DestroyBuffer(r.device.Logical, r.Buffer, nil)
98 r.Buffer = 0
99 }
100 if r.Memory != 0 {
101 r.device.Dispatch.FreeMemory(r.device.Logical, r.Memory, nil)
102 r.Memory = 0
103 }
104}