gpu/backend: move backend interface types to a separate package

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

gpu/backend/backend.go

@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package backend
+
+import (
+	"image"
+	"time"
+)
+
+// Device represents the abstraction of underlying GPU
+// APIs such as OpenGL, Direct3D useful for rendering Gio
+// operations.
+type Device interface {
+	BeginFrame()
+	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)
+	CurrentFramebuffer() Framebuffer
+	NewFramebuffer(tex Texture, depthBits int) (Framebuffer, error)
+	NewImmutableBuffer(typ BufferBinding, data []byte) (Buffer, error)
+	NewBuffer(typ BufferBinding, size int) (Buffer, error)
+	NewProgram(vertexShader, fragmentShader ShaderSources) (Program, error)
+	NewInputLayout(vertexShader ShaderSources, layout []InputDesc) (InputLayout, error)
+
+	DepthFunc(f DepthFunc)
+	ClearColor(r, g, b, a float32)
+	ClearDepth(d float32)
+	Clear(buffers BufferAttachments)
+	Viewport(x, y, width, height int)
+	DrawArrays(mode DrawMode, off, count int)
+	DrawElements(mode DrawMode, off, count int)
+	SetBlend(enable bool)
+	SetDepthTest(enable bool)
+	DepthMask(mask bool)
+	BlendFunc(sfactor, dfactor BlendFactor)
+
+	BindInputLayout(i InputLayout)
+	BindProgram(p Program)
+	BindFramebuffer(f Framebuffer)
+	BindTexture(unit int, t Texture)
+	BindVertexBuffer(b Buffer, stride, offset int)
+	BindIndexBuffer(b Buffer)
+}
+
+type ShaderSources struct {
+	GLES2       string
+	HLSL        []byte
+	Uniforms    []UniformLocation
+	UniformSize int
+	Inputs      []InputLocation
+	Textures    []TextureBinding
+}
+
+type TextureBinding struct {
+	Name    string
+	Binding int
+}
+
+type UniformLocation struct {
+	Name   string
+	Type   DataType
+	Size   int
+	Offset int
+}
+
+type InputLocation struct {
+	// For GLSL.
+	Name     string
+	Location int
+	// For HLSL.
+	Semantic      string
+	SemanticIndex int
+
+	Type DataType
+	Size int
+}
+
+// InputDesc describes a vertex attribute as laid out in a Buffer.
+type InputDesc struct {
+	Type DataType
+	Size int
+
+	Offset int
+}
+
+// InputLayout is the backend specific representation of the mapping
+// between Buffers and shader attributes.
+type InputLayout interface {
+	Release()
+}
+
+type BlendFactor uint8
+
+type DrawMode uint8
+
+type BufferAttachments uint
+
+type TextureFilter uint8
+type TextureFormat uint8
+
+type BufferBinding uint8
+
+type DataType uint8
+
+type DepthFunc uint8
+
+type Features uint
+
+type Caps struct {
+	Features       Features
+	MaxTextureSize int
+}
+
+type Program interface {
+	Release()
+	SetVertexUniforms(buf Buffer)
+	SetFragmentUniforms(buf Buffer)
+}
+
+type Buffer interface {
+	Release()
+	Upload(data []byte)
+}
+
+type Framebuffer interface {
+	Invalidate()
+	Release()
+	ReadPixels(src image.Rectangle, pixels []byte) error
+}
+
+type Timer interface {
+	Begin()
+	End()
+	Duration() (time.Duration, bool)
+	Release()
+}
+
+type Texture interface {
+	Upload(img *image.RGBA)
+	Release()
+}
+
+const (
+	BufferAttachmentColor BufferAttachments = 1 << iota
+	BufferAttachmentDepth
+)
+
+const (
+	DepthFuncGreater DepthFunc = iota
+)
+
+const (
+	DataTypeFloat DataType = iota
+	DataTypeShort
+)
+
+const (
+	BufferBindingIndices BufferBinding = 1 << iota
+	BufferBindingVertices
+	BufferBindingUniforms
+	BufferBindingTexture
+	BufferBindingFramebuffer
+)
+
+const (
+	TextureFormatSRGB TextureFormat = iota
+	TextureFormatFloat
+)
+
+const (
+	FilterNearest TextureFilter = iota
+	FilterLinear
+)
+
+const (
+	FeatureTimers Features = iota
+)
+
+const (
+	DrawModeTriangleStrip DrawMode = iota
+	DrawModeTriangles
+)
+
+const (
+	BlendFactorOne BlendFactor = iota
+	BlendFactorOneMinusSrcAlpha
+	BlendFactorZero
+	BlendFactorDstColor
+)
+
+func (f Features) Has(feats Features) bool {
+	return f&feats == feats
+}