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Fix sRGB blending and cleanup the relevant code (#2070)
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* Fix sRGBA blending on Mac

* Clean up handling of sRGB support

* Assume sRGB support if any extension has sRGB in it

* improve logging very slightly
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@emilk
emilk authored Sep 21, 2022
1 parent 4aae638 commit 990a8c8
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Showing 2 changed files with 56 additions and 46 deletions.
89 changes: 43 additions & 46 deletions crates/egui_glow/src/painter.rs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
#![allow(clippy::collapsible_else_if)]
#![allow(unsafe_code)]

use std::{collections::HashMap, sync::Arc};
Expand Down Expand Up @@ -53,7 +54,7 @@ pub struct Painter {
is_webgl_1: bool,
is_embedded: bool,
vao: crate::vao::VertexArrayObject,
srgb_support: bool,
srgb_textures: bool,
post_process: Option<PostProcess>,
vbo: glow::Buffer,
element_array_buffer: glow::Buffer,
Expand Down Expand Up @@ -112,45 +113,41 @@ impl Painter {
crate::check_for_gl_error_even_in_release!(&gl, "before Painter::new");

let max_texture_side = unsafe { gl.get_parameter_i32(glow::MAX_TEXTURE_SIZE) } as usize;
let shader = shader_version.unwrap_or_else(|| ShaderVersion::get(&gl));
let is_webgl_1 = shader == ShaderVersion::Es100;
let header = shader.version_declaration();
let shader_version = shader_version.unwrap_or_else(|| ShaderVersion::get(&gl));
let is_webgl_1 = shader_version == ShaderVersion::Es100;
let header = shader_version.version_declaration();
tracing::debug!("Shader header: {:?}.", header);
// Previously checking srgb_support on WebGL only, now we have to check on other GL | ES as well.
let srgb_support = gl.supported_extensions().contains("EXT_sRGB")
|| gl.supported_extensions().contains("GL_EXT_sRGB")
|| gl
.supported_extensions()
.contains("GL_ARB_framebuffer_sRGB");
tracing::debug!("SRGB Support: {:?}.", srgb_support);

let (post_process, srgb_support_define) = match (shader, srgb_support) {
// WebGL2 support sRGB default
(ShaderVersion::Es300, _) | (ShaderVersion::Es100, true) => unsafe {
// Add sRGB support marker for fragment shader
if let Some(size) = pp_fb_extent {
tracing::debug!("WebGL with sRGB enabled. Turning on post processing for linear framebuffer blending.");
// install post process to correct sRGB color:
(
Some(PostProcess::new(
gl.clone(),
shader_prefix,
is_webgl_1,
size,
)?),
"#define SRGB_SUPPORTED",
)
} else {
tracing::debug!("WebGL or OpenGL ES detected but PostProcess disabled because dimension is None");
(None, "")
}
},

// WebGL1 without sRGB support disable postprocess and use fallback shader
(ShaderVersion::Es100, false) => (None, ""),

// OpenGL 2.1 or above always support sRGB so add sRGB support marker
_ => (None, "#define SRGB_SUPPORTED"),
let supported_extensions = gl.supported_extensions();
tracing::trace!("OpenGL extensions: {supported_extensions:?}");
let srgb_textures = shader_version == ShaderVersion::Es300 // WebGL2 always support sRGB
|| supported_extensions.iter().any(|extension| {
// EXT_sRGB, GL_ARB_framebuffer_sRGB, GL_EXT_sRGB, GL_EXT_texture_sRGB_decode, …
extension.contains("sRGB")
});
tracing::debug!("SRGB Support: {:?}", srgb_textures);

let (post_process, srgb_support_define) = if shader_version.is_embedded() {
// WebGL doesn't support linear framebuffer blending… but maybe we can emulate it with `PostProcess`?

if let Some(size) = pp_fb_extent {
tracing::debug!("WebGL with sRGB support. Turning on post processing for linear framebuffer blending.");
// install post process to correct sRGB color:
(
Some(unsafe { PostProcess::new(gl.clone(), shader_prefix, is_webgl_1, size)? }),
"#define SRGB_SUPPORTED",
)
} else {
tracing::warn!("WebGL or OpenGL ES detected but PostProcess disabled because dimension is None. Linear framebuffer blending will not be supported.");
(None, "")
}
} else {
if srgb_textures {
(None, "#define SRGB_SUPPORTED")
} else {
tracing::warn!("sRGB aware texture filtering not available");
(None, "")
}
};

unsafe {
Expand All @@ -161,7 +158,7 @@ impl Painter {
"{}\n{}\n{}\n{}",
header,
shader_prefix,
if shader.is_new_shader_interface() {
if shader_version.is_new_shader_interface() {
"#define NEW_SHADER_INTERFACE\n"
} else {
""
Expand All @@ -177,7 +174,7 @@ impl Painter {
header,
shader_prefix,
srgb_support_define,
if shader.is_new_shader_interface() {
if shader_version.is_new_shader_interface() {
"#define NEW_SHADER_INTERFACE\n"
} else {
""
Expand Down Expand Up @@ -239,9 +236,9 @@ impl Painter {
u_screen_size,
u_sampler,
is_webgl_1,
is_embedded: matches!(shader, ShaderVersion::Es100 | ShaderVersion::Es300),
is_embedded: shader_version.is_embedded(),
vao,
srgb_support,
srgb_textures,
post_process,
vbo,
element_array_buffer,
Expand Down Expand Up @@ -591,16 +588,16 @@ impl Painter {
check_for_gl_error!(&self.gl, "tex_parameter");

let (internal_format, src_format) = if self.is_webgl_1 {
let format = if self.srgb_support {
let format = if self.srgb_textures {
glow::SRGB_ALPHA
} else {
glow::RGBA
};
(format, format)
} else if !self.srgb_support {
(glow::RGBA8, glow::RGBA)
} else {
} else if self.srgb_textures {
(glow::SRGB8_ALPHA8, glow::RGBA)
} else {
(glow::RGBA8, glow::RGBA)
};

self.gl.pixel_store_i32(glow::UNPACK_ALIGNMENT, 1);
Expand Down
13 changes: 13 additions & 0 deletions crates/egui_glow/src/shader_version.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,14 @@ use std::convert::TryInto;
#[allow(dead_code)]
pub enum ShaderVersion {
Gl120,

/// OpenGL 1.4 or later
Gl140,

/// e.g. WebGL1
Es100,

/// e.g. WebGL2
Es300,
}

Expand Down Expand Up @@ -70,6 +76,13 @@ impl ShaderVersion {
Self::Es300 | Self::Gl140 => true,
}
}

pub fn is_embedded(&self) -> bool {
match self {
Self::Gl120 | Self::Gl140 => false,
Self::Es100 | Self::Es300 => true,
}
}
}

#[test]
Expand Down

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