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// SPDX-License-Identifier: Unlicense OR MIT
package driver
import (
"errors"
"image"
"time"
"gioui.org/internal/f32color"
"gioui.org/shader"
)
// Device represents the abstraction of underlying GPU
// APIs such as OpenGL, Direct3D useful for rendering Gio
// operations.
type Device interface {
BeginFrame(target RenderTarget, clear bool, viewport image.Point) Texture
EndFrame()
Caps() Caps
NewTimer() Timer
// IsContinuousTime reports whether all timer measurements
// are valid at the point of call.
IsTimeContinuous() bool
NewTexture(format TextureFormat, width, height int, minFilter, magFilter TextureFilter, bindings BufferBinding) (Texture, error)
NewImmutableBuffer(typ BufferBinding, data []byte) (Buffer, error)
NewBuffer(typ BufferBinding, size int) (Buffer, error)
NewComputeProgram(shader shader.Sources) (Program, error)
NewVertexShader(src shader.Sources) (VertexShader, error)
NewFragmentShader(src shader.Sources) (FragmentShader, error)
NewPipeline(desc PipelineDesc) (Pipeline, error)
Viewport(x, y, width, height int)
DrawArrays(off, count int)
DrawElements(off, count int)
BeginRenderPass(t Texture, desc LoadDesc)
EndRenderPass()
PrepareTexture(t Texture)
BindProgram(p Program)
BindPipeline(p Pipeline)
BindTexture(unit int, t Texture)
BindVertexBuffer(b Buffer, offset int)
BindIndexBuffer(b Buffer)
BindImageTexture(unit int, texture Texture)
BindUniforms(buf Buffer)
BindStorageBuffer(binding int, buf Buffer)
BeginCompute()
EndCompute()
CopyTexture(dst Texture, dstOrigin image.Point, src Texture, srcRect image.Rectangle)
DispatchCompute(x, y, z int)
Release()
}
var ErrDeviceLost = errors.New("GPU device lost")
type LoadDesc struct {
Action LoadAction
ClearColor f32color.RGBA
}
type Pipeline interface {
Release()
}
type PipelineDesc struct {
VertexShader VertexShader
FragmentShader FragmentShader
VertexLayout VertexLayout
BlendDesc BlendDesc
PixelFormat TextureFormat
Topology Topology
}
type VertexLayout struct {
Inputs []InputDesc
Stride int
}
// InputDesc describes a vertex attribute as laid out in a Buffer.
type InputDesc struct {
Type shader.DataType
Size int
Offset int
}
type BlendDesc struct {
Enable bool
SrcFactor, DstFactor BlendFactor
}
type BlendFactor uint8
type Topology uint8
type TextureFilter uint8
type TextureFormat uint8
type BufferBinding uint8
type LoadAction uint8
type Features uint
type Caps struct {
// BottomLeftOrigin is true if the driver has the origin in the lower left
// corner. The OpenGL driver returns true.
BottomLeftOrigin bool
Features Features
MaxTextureSize int
}
type VertexShader interface {
Release()
}
type FragmentShader interface {
Release()
}
type Program interface {
Release()
}
type Buffer interface {
Release()
Upload(data []byte)
Download(data []byte) error
}
type Timer interface {
Begin()
End()
Duration() (time.Duration, bool)
Release()
}
type Texture interface {
RenderTarget
Upload(offset, size image.Point, pixels []byte, stride int)
ReadPixels(src image.Rectangle, pixels []byte, stride int) error
Release()
}
const (
BufferBindingIndices BufferBinding = 1 << iota
BufferBindingVertices
BufferBindingUniforms
BufferBindingTexture
BufferBindingFramebuffer
BufferBindingShaderStorageRead
BufferBindingShaderStorageWrite
)
const (
TextureFormatSRGBA TextureFormat = iota
TextureFormatFloat
TextureFormatRGBA8
// TextureFormatOutput denotes the format used by the output framebuffer.
TextureFormatOutput
)
const (
FilterNearest TextureFilter = iota
FilterLinear
)
const (
FeatureTimers Features = 1 << iota
FeatureFloatRenderTargets
FeatureCompute
FeatureSRGB
)
const (
TopologyTriangleStrip Topology = iota
TopologyTriangles
)
const (
BlendFactorOne BlendFactor = iota
BlendFactorOneMinusSrcAlpha
BlendFactorZero
BlendFactorDstColor
)
const (
LoadActionKeep LoadAction = iota
LoadActionClear
LoadActionInvalidate
)
var ErrContentLost = errors.New("buffer content lost")
func (f Features) Has(feats Features) bool {
return f&feats == feats
}
func DownloadImage(d Device, t Texture, img *image.RGBA) error {
r := img.Bounds()
if err := t.ReadPixels(r, img.Pix, img.Stride); err != nil {
return err
}
if d.Caps().BottomLeftOrigin {
// OpenGL origin is in the lower-left corner. Flip the image to
// match.
flipImageY(r.Dx()*4, r.Dy(), img.Pix)
}
return nil
}
func flipImageY(stride, height int, pixels []byte) {
// Flip image in y-direction. OpenGL's origin is in the lower
// left corner.
row := make([]uint8, stride)
for y := 0; y < height/2; y++ {
y1 := height - y - 1
dest := y1 * stride
src := y * stride
copy(row, pixels[dest:])
copy(pixels[dest:], pixels[src:src+len(row)])
copy(pixels[src:], row)
}
}
func UploadImage(t Texture, offset image.Point, img *image.RGBA) {
var pixels []byte
size := img.Bounds().Size()
min := img.Rect.Min
start := img.PixOffset(min.X, min.Y)
end := img.PixOffset(min.X+size.X, min.Y+size.Y-1)
pixels = img.Pix[start:end]
t.Upload(offset, size, pixels, img.Stride)
}
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