forked from joejulian/gio
internal/srgb: move app/internal/srgb
We're about to move app/headless to gpu/headless, and it imports package srgb indirectly. Signed-off-by: Elias Naur <mail@eliasnaur.com>
This commit is contained in:
Elias Naur
@@ -0,0 +1,198 @@
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// SPDX-License-Identifier: Unlicense OR MIT
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package srgb
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import (
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"fmt"
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"runtime"
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"strings"
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"gioui.org/internal/glimpl"
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"gioui.org/internal/unsafe"
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)
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// FBO implements an intermediate sRGB FBO
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// for gamma-correct rendering on platforms without
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// sRGB enabled native framebuffers.
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type FBO struct {
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c *glimpl.Functions
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width, height int
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frameBuffer glimpl.Framebuffer
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depthBuffer glimpl.Renderbuffer
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colorTex glimpl.Texture
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blitted bool
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quad glimpl.Buffer
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prog glimpl.Program
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gl3 bool
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}
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func New(ctx glimpl.Context) (*FBO, error) {
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f, err := glimpl.NewFunctions(ctx)
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if err != nil {
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return nil, err
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}
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var gl3 bool
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glVer := f.GetString(glimpl.VERSION)
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ver, _, err := glimpl.ParseGLVersion(glVer)
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if err != nil {
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return nil, err
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}
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if ver[0] >= 3 {
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gl3 = true
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} else {
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exts := f.GetString(glimpl.EXTENSIONS)
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if !strings.Contains(exts, "EXT_sRGB") {
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return nil, fmt.Errorf("no support for OpenGL ES 3 nor EXT_sRGB")
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}
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}
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s := &FBO{
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c: f,
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gl3: gl3,
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frameBuffer: f.CreateFramebuffer(),
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colorTex: f.CreateTexture(),
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depthBuffer: f.CreateRenderbuffer(),
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}
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f.BindTexture(glimpl.TEXTURE_2D, s.colorTex)
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f.TexParameteri(glimpl.TEXTURE_2D, glimpl.TEXTURE_WRAP_S, glimpl.CLAMP_TO_EDGE)
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f.TexParameteri(glimpl.TEXTURE_2D, glimpl.TEXTURE_WRAP_T, glimpl.CLAMP_TO_EDGE)
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f.TexParameteri(glimpl.TEXTURE_2D, glimpl.TEXTURE_MAG_FILTER, glimpl.NEAREST)
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f.TexParameteri(glimpl.TEXTURE_2D, glimpl.TEXTURE_MIN_FILTER, glimpl.NEAREST)
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return s, nil
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}
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func (s *FBO) Blit() {
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if !s.blitted {
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prog, err := glimpl.CreateProgram(s.c, blitVSrc, blitFSrc, []string{"pos", "uv"})
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if err != nil {
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panic(err)
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}
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s.prog = prog
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s.c.UseProgram(prog)
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s.c.Uniform1i(s.c.GetUniformLocation(prog, "tex"), 0)
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s.quad = s.c.CreateBuffer()
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s.c.BindBuffer(glimpl.ARRAY_BUFFER, s.quad)
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coords := unsafe.BytesView([]float32{
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-1, +1, 0, 1,
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+1, +1, 1, 1,
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-1, -1, 0, 0,
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+1, -1, 1, 0,
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})
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s.c.BufferData(glimpl.ARRAY_BUFFER, len(coords), glimpl.STATIC_DRAW)
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s.c.BufferSubData(glimpl.ARRAY_BUFFER, 0, coords)
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s.blitted = true
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}
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s.c.BindFramebuffer(glimpl.FRAMEBUFFER, glimpl.Framebuffer{})
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s.c.UseProgram(s.prog)
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s.c.BindTexture(glimpl.TEXTURE_2D, s.colorTex)
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s.c.BindBuffer(glimpl.ARRAY_BUFFER, s.quad)
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s.c.VertexAttribPointer(0 /* pos */, 2, glimpl.FLOAT, false, 4*4, 0)
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s.c.VertexAttribPointer(1 /* uv */, 2, glimpl.FLOAT, false, 4*4, 4*2)
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s.c.EnableVertexAttribArray(0)
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s.c.EnableVertexAttribArray(1)
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s.c.DrawArrays(glimpl.TRIANGLE_STRIP, 0, 4)
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s.c.BindTexture(glimpl.TEXTURE_2D, glimpl.Texture{})
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s.c.DisableVertexAttribArray(0)
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s.c.DisableVertexAttribArray(1)
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s.c.BindFramebuffer(glimpl.FRAMEBUFFER, s.frameBuffer)
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s.c.InvalidateFramebuffer(glimpl.FRAMEBUFFER, glimpl.COLOR_ATTACHMENT0)
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s.c.InvalidateFramebuffer(glimpl.FRAMEBUFFER, glimpl.DEPTH_ATTACHMENT)
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// The Android emulator requires framebuffer 0 bound at eglSwapBuffer time.
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// Bind the sRGB framebuffer again in afterPresent.
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s.c.BindFramebuffer(glimpl.FRAMEBUFFER, glimpl.Framebuffer{})
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}
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func (s *FBO) AfterPresent() {
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s.c.BindFramebuffer(glimpl.FRAMEBUFFER, s.frameBuffer)
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}
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func (s *FBO) Refresh(w, h int) error {
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s.width, s.height = w, h
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if w == 0 || h == 0 {
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return nil
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}
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s.c.BindTexture(glimpl.TEXTURE_2D, s.colorTex)
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if s.gl3 {
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s.c.TexImage2D(glimpl.TEXTURE_2D, 0, glimpl.SRGB8_ALPHA8, w, h, glimpl.RGBA, glimpl.UNSIGNED_BYTE)
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} else /* EXT_sRGB */ {
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s.c.TexImage2D(glimpl.TEXTURE_2D, 0, glimpl.SRGB_ALPHA_EXT, w, h, glimpl.SRGB_ALPHA_EXT, glimpl.UNSIGNED_BYTE)
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}
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currentRB := glimpl.Renderbuffer(s.c.GetBinding(glimpl.RENDERBUFFER_BINDING))
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s.c.BindRenderbuffer(glimpl.RENDERBUFFER, s.depthBuffer)
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s.c.RenderbufferStorage(glimpl.RENDERBUFFER, glimpl.DEPTH_COMPONENT16, w, h)
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s.c.BindRenderbuffer(glimpl.RENDERBUFFER, currentRB)
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s.c.BindFramebuffer(glimpl.FRAMEBUFFER, s.frameBuffer)
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s.c.FramebufferTexture2D(glimpl.FRAMEBUFFER, glimpl.COLOR_ATTACHMENT0, glimpl.TEXTURE_2D, s.colorTex, 0)
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s.c.FramebufferRenderbuffer(glimpl.FRAMEBUFFER, glimpl.DEPTH_ATTACHMENT, glimpl.RENDERBUFFER, s.depthBuffer)
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if st := s.c.CheckFramebufferStatus(glimpl.FRAMEBUFFER); st != glimpl.FRAMEBUFFER_COMPLETE {
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return fmt.Errorf("sRGB framebuffer incomplete (%dx%d), status: %#x error: %x", s.width, s.height, st, s.c.GetError())
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}
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if runtime.GOOS == "js" {
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// With macOS Safari, rendering to and then reading from a SRGB8_ALPHA8
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// texture result in twice gamma corrected colors. Using a plain RGBA
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// texture seems to work.
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s.c.ClearColor(.5, .5, .5, 1.0)
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s.c.Clear(glimpl.COLOR_BUFFER_BIT)
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var pixel [4]byte
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s.c.ReadPixels(0, 0, 1, 1, glimpl.RGBA, glimpl.UNSIGNED_BYTE, pixel[:])
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if pixel[0] == 128 { // Correct sRGB color value is ~188
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s.c.TexImage2D(glimpl.TEXTURE_2D, 0, glimpl.RGBA, w, h, glimpl.RGBA, glimpl.UNSIGNED_BYTE)
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if st := s.c.CheckFramebufferStatus(glimpl.FRAMEBUFFER); st != glimpl.FRAMEBUFFER_COMPLETE {
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return fmt.Errorf("fallback RGBA framebuffer incomplete (%dx%d), status: %#x error: %x", s.width, s.height, st, s.c.GetError())
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}
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}
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}
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return nil
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}
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func (s *FBO) Release() {
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s.c.DeleteFramebuffer(s.frameBuffer)
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s.c.DeleteTexture(s.colorTex)
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s.c.DeleteRenderbuffer(s.depthBuffer)
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if s.blitted {
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s.c.DeleteBuffer(s.quad)
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s.c.DeleteProgram(s.prog)
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}
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s.c = nil
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}
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const (
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blitVSrc = `
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#version 100
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precision highp float;
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attribute vec2 pos;
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attribute vec2 uv;
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varying vec2 vUV;
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void main() {
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gl_Position = vec4(pos, 0, 1);
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vUV = uv;
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}
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`
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blitFSrc = `
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#version 100
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precision mediump float;
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uniform sampler2D tex;
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varying vec2 vUV;
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vec3 gamma(vec3 rgb) {
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vec3 exp = vec3(1.055)*pow(rgb, vec3(0.41666)) - vec3(0.055);
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vec3 lin = rgb * vec3(12.92);
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bvec3 cut = lessThan(rgb, vec3(0.0031308));
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return vec3(cut.r ? lin.r : exp.r, cut.g ? lin.g : exp.g, cut.b ? lin.b : exp.b);
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}
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void main() {
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vec4 col = texture2D(tex, vUV);
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vec3 rgb = col.rgb;
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rgb = gamma(rgb);
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gl_FragColor = vec4(rgb, col.a);
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}
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`
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)
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