You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
196 lines
5.5 KiB
Go
196 lines
5.5 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
|
|
|
|
package srgb
|
|
|
|
import (
|
|
"fmt"
|
|
"runtime"
|
|
"strings"
|
|
|
|
"gioui.org/app/internal/glimpl"
|
|
"gioui.org/gpu/gl"
|
|
"gioui.org/internal/unsafe"
|
|
)
|
|
|
|
// FBO implements an intermediate sRGB FBO
|
|
// for gamma-correct rendering on platforms without
|
|
// sRGB enabled native framebuffers.
|
|
type FBO struct {
|
|
c *glimpl.Functions
|
|
width, height int
|
|
frameBuffer gl.Framebuffer
|
|
depthBuffer gl.Renderbuffer
|
|
colorTex gl.Texture
|
|
blitted bool
|
|
quad gl.Buffer
|
|
prog gl.Program
|
|
gl3 bool
|
|
}
|
|
|
|
func New(f *glimpl.Functions) (*FBO, error) {
|
|
var gl3 bool
|
|
glVer := f.GetString(gl.VERSION)
|
|
ver, _, err := gl.ParseGLVersion(glVer)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if ver[0] >= 3 {
|
|
gl3 = true
|
|
} else {
|
|
exts := f.GetString(gl.EXTENSIONS)
|
|
if !strings.Contains(exts, "EXT_sRGB") {
|
|
return nil, fmt.Errorf("no support for OpenGL ES 3 nor EXT_sRGB")
|
|
}
|
|
}
|
|
s := &FBO{
|
|
c: f,
|
|
gl3: gl3,
|
|
frameBuffer: f.CreateFramebuffer(),
|
|
colorTex: f.CreateTexture(),
|
|
depthBuffer: f.CreateRenderbuffer(),
|
|
}
|
|
f.BindTexture(gl.TEXTURE_2D, s.colorTex)
|
|
f.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
|
|
f.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
|
|
f.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
|
|
f.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
|
|
return s, nil
|
|
}
|
|
|
|
func (s *FBO) Blit() {
|
|
if !s.blitted {
|
|
prog, err := gl.CreateProgram(s.c, blitVSrc, blitFSrc, []string{"pos", "uv"})
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
s.prog = prog
|
|
s.c.UseProgram(prog)
|
|
s.c.Uniform1i(gl.GetUniformLocation(s.c, prog, "tex"), 0)
|
|
s.quad = s.c.CreateBuffer()
|
|
s.c.BindBuffer(gl.ARRAY_BUFFER, s.quad)
|
|
s.c.BufferData(gl.ARRAY_BUFFER,
|
|
unsafe.BytesView([]float32{
|
|
-1, +1, 0, 1,
|
|
+1, +1, 1, 1,
|
|
-1, -1, 0, 0,
|
|
+1, -1, 1, 0,
|
|
}),
|
|
gl.STATIC_DRAW)
|
|
s.blitted = true
|
|
}
|
|
s.c.BindFramebuffer(gl.FRAMEBUFFER, gl.Framebuffer{})
|
|
s.c.UseProgram(s.prog)
|
|
s.c.BindTexture(gl.TEXTURE_2D, s.colorTex)
|
|
s.c.BindBuffer(gl.ARRAY_BUFFER, s.quad)
|
|
s.c.VertexAttribPointer(0 /* pos */, 2, gl.FLOAT, false, 4*4, 0)
|
|
s.c.VertexAttribPointer(1 /* uv */, 2, gl.FLOAT, false, 4*4, 4*2)
|
|
s.c.EnableVertexAttribArray(0)
|
|
s.c.EnableVertexAttribArray(1)
|
|
s.c.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
|
|
s.c.BindTexture(gl.TEXTURE_2D, gl.Texture{})
|
|
s.c.DisableVertexAttribArray(0)
|
|
s.c.DisableVertexAttribArray(1)
|
|
s.c.BindFramebuffer(gl.FRAMEBUFFER, s.frameBuffer)
|
|
s.c.InvalidateFramebuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0)
|
|
s.c.InvalidateFramebuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT)
|
|
// The Android emulator requires framebuffer 0 bound at eglSwapBuffer time.
|
|
// Bind the sRGB framebuffer again in afterPresent.
|
|
s.c.BindFramebuffer(gl.FRAMEBUFFER, gl.Framebuffer{})
|
|
}
|
|
|
|
func (s *FBO) AfterPresent() {
|
|
s.c.BindFramebuffer(gl.FRAMEBUFFER, s.frameBuffer)
|
|
}
|
|
|
|
func (s *FBO) Refresh(w, h int) error {
|
|
s.width, s.height = w, h
|
|
if w == 0 || h == 0 {
|
|
return nil
|
|
}
|
|
s.c.BindTexture(gl.TEXTURE_2D, s.colorTex)
|
|
if s.gl3 {
|
|
s.c.TexImage2D(gl.TEXTURE_2D, 0, gl.SRGB8_ALPHA8, w, h, gl.RGBA, gl.UNSIGNED_BYTE, nil)
|
|
} else /* EXT_sRGB */ {
|
|
s.c.TexImage2D(gl.TEXTURE_2D, 0, gl.SRGB_ALPHA_EXT, w, h, gl.SRGB_ALPHA_EXT, gl.UNSIGNED_BYTE, nil)
|
|
}
|
|
currentRB := gl.Renderbuffer(s.c.GetBinding(gl.RENDERBUFFER_BINDING))
|
|
s.c.BindRenderbuffer(gl.RENDERBUFFER, s.depthBuffer)
|
|
s.c.RenderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, w, h)
|
|
s.c.BindRenderbuffer(gl.RENDERBUFFER, currentRB)
|
|
s.c.BindFramebuffer(gl.FRAMEBUFFER, s.frameBuffer)
|
|
s.c.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, s.colorTex, 0)
|
|
s.c.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, s.depthBuffer)
|
|
if st := s.c.CheckFramebufferStatus(gl.FRAMEBUFFER); st != gl.FRAMEBUFFER_COMPLETE {
|
|
return fmt.Errorf("sRGB framebuffer incomplete (%dx%d), status: %#x error: %x", s.width, s.height, st, s.c.GetError())
|
|
}
|
|
|
|
if runtime.GOOS == "js" {
|
|
// With macOS Safari, rendering to and then reading from a SRGB8_ALPHA8
|
|
// texture result in twice gamma corrected colors. Using a plain RGBA
|
|
// texture seems to work.
|
|
s.c.ClearColor(.5, .5, .5, 1.0)
|
|
s.c.Clear(gl.COLOR_BUFFER_BIT)
|
|
var pixel [4]byte
|
|
s.c.ReadPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, pixel[:])
|
|
if pixel[0] == 128 { // Correct sRGB color value is ~188
|
|
s.c.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, w, h, gl.RGBA, gl.UNSIGNED_BYTE, nil)
|
|
if st := s.c.CheckFramebufferStatus(gl.FRAMEBUFFER); st != gl.FRAMEBUFFER_COMPLETE {
|
|
return fmt.Errorf("fallback RGBA framebuffer incomplete (%dx%d), status: %#x error: %x", s.width, s.height, st, s.c.GetError())
|
|
}
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func (s *FBO) Release() {
|
|
s.c.DeleteFramebuffer(s.frameBuffer)
|
|
s.c.DeleteTexture(s.colorTex)
|
|
s.c.DeleteRenderbuffer(s.depthBuffer)
|
|
if s.blitted {
|
|
s.c.DeleteBuffer(s.quad)
|
|
s.c.DeleteProgram(s.prog)
|
|
}
|
|
s.c = nil
|
|
}
|
|
|
|
const (
|
|
blitVSrc = `
|
|
#version 100
|
|
|
|
precision highp float;
|
|
|
|
attribute vec2 pos;
|
|
attribute vec2 uv;
|
|
|
|
varying vec2 vUV;
|
|
|
|
void main() {
|
|
gl_Position = vec4(pos, 0, 1);
|
|
vUV = uv;
|
|
}
|
|
`
|
|
blitFSrc = `
|
|
#version 100
|
|
|
|
precision mediump float;
|
|
|
|
uniform sampler2D tex;
|
|
varying vec2 vUV;
|
|
|
|
vec3 gamma(vec3 rgb) {
|
|
vec3 exp = vec3(1.055)*pow(rgb, vec3(0.41666)) - vec3(0.055);
|
|
vec3 lin = rgb * vec3(12.92);
|
|
bvec3 cut = lessThan(rgb, vec3(0.0031308));
|
|
return vec3(cut.r ? lin.r : exp.r, cut.g ? lin.g : exp.g, cut.b ? lin.b : exp.b);
|
|
}
|
|
|
|
void main() {
|
|
vec4 col = texture2D(tex, vUV);
|
|
vec3 rgb = col.rgb;
|
|
rgb = gamma(rgb);
|
|
gl_FragColor = vec4(rgb, col.a);
|
|
}
|
|
`
|
|
)
|