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[egui_web] sRGBA: blend vertex colors in linear space

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This commit is contained in:
Emil Ernerfeldt 2020-08-29 11:10:11 +02:00
parent d5a1385870
commit 3d7b5ea6fe
1 changed files with 42 additions and 14 deletions
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56
egui_web/src/webgl.rs
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@ -61,38 +61,66 @@ impl Painter {
&gl,
Gl::VERTEX_SHADER,
r#"
precision mediump float;
uniform vec2 u_screen_size;
uniform vec2 u_tex_size;
attribute vec2 a_pos;
attribute vec2 a_tc;
attribute vec4 a_color;
varying vec4 v_color;
attribute vec4 a_srgba;
varying vec4 v_rgba;
varying vec2 v_tc;
// 0-1 linear from 0-255 sRGB
vec3 linear_from_srgb(vec3 srgb) {
bvec3 cutoff = lessThan(srgb, vec3(10.31475));
vec3 lower = srgb / vec3(3294.6);
vec3 higher = pow((srgb + vec3(14.025)) / vec3(269.025), vec3(2.4));
return mix(higher, lower, vec3(cutoff));
}
vec4 linear_from_srgba(vec4 srgba) {
return vec4(linear_from_srgb(srgba.rgb), srgba.a / 255.0);
}
void main() {
gl_Position = vec4(
2.0 * a_pos.x / u_screen_size.x - 1.0,
1.0 - 2.0 * a_pos.y / u_screen_size.y,
0.0,
1.0);
v_color = a_color;
v_rgba = linear_from_srgba(a_srgba);
v_tc = a_tc / u_tex_size;
}
"#,
)?;
let frag_shader = compile_shader(
&gl,
Gl::FRAGMENT_SHADER,
r#"
precision mediump float;
uniform sampler2D u_sampler;
precision highp float;
varying vec4 v_color;
varying vec4 v_rgba;
varying vec2 v_tc;
// 0-255 sRGB from 0-1 linear
vec3 srgb_from_linear(vec3 rgb) {
bvec3 cutoff = lessThan(rgb, vec3(0.0031308));
vec3 lower = rgb * vec3(3294.6);
vec3 higher = vec3(269.025) * pow(rgb, vec3(1.0 / 2.4)) - vec3(14.025);
return mix(higher, lower, vec3(cutoff));
}
vec4 srgba_from_linear(vec4 rgba) {
return vec4(srgb_from_linear(rgba.rgb), 255.0 * rgba.a);
}
void main() {
gl_FragColor = v_color;
gl_FragColor *= texture2D(u_sampler, v_tc).a;
gl_FragColor = srgba_from_linear(v_rgba * texture2D(u_sampler, v_tc).a) / 255.0;
}
"#,
)?;
let program = link_program(&gl, [vert_shader, frag_shader].iter())?;
let index_buffer = gl.create_buffer().ok_or("failed to create index_buffer")?;
let pos_buffer = gl.create_buffer().ok_or("failed to create pos_buffer")?;
@ -196,7 +224,7 @@ impl Painter {
self.canvas.width() as i32,
self.canvas.height() as i32,
);
// TODO: sRGBA
// TODO: sRGBA ?
gl.clear_color(
bg_color.r as f32 / 255.0,
bg_color.g as f32 / 255.0,
@ -336,22 +364,22 @@ impl Painter {
gl.bind_buffer(Gl::ARRAY_BUFFER, Some(&self.color_buffer));
gl.buffer_data_with_array_buffer_view(Gl::ARRAY_BUFFER, &colors_array, Gl::STREAM_DRAW);
let a_color_loc = gl.get_attrib_location(&self.program, "a_color");
assert!(a_color_loc >= 0);
let a_color_loc = a_color_loc as u32;
let a_srgba_loc = gl.get_attrib_location(&self.program, "a_srgba");
assert!(a_srgba_loc >= 0);
let a_srgba_loc = a_srgba_loc as u32;
let normalize = true;
let normalize = false;
let stride = 0;
let offset = 0;
gl.vertex_attrib_pointer_with_i32(
a_color_loc,
a_srgba_loc,
4,
Gl::UNSIGNED_BYTE,
normalize,
stride,
offset,
);
gl.enable_vertex_attrib_array(a_color_loc);
gl.enable_vertex_attrib_array(a_srgba_loc);
// --------------------------------------------------------------------