Use Rgba (4xf32) instead of Color32 in all interfaces

This simplifies a few things, but some benchmarks gets worse,
probably due to the increased memory use (and thus more cache misses).

I don't plan to merge this, but leave it here as an experiment

egui_glium/src/lib.rs

@@ -504,7 +504,7 @@ impl EguiGlium {
     pub fn on_event(&mut self, event: &glium::glutin::event::WindowEvent<'_>) {
         crate::input_to_egui(
             self.egui_ctx.pixels_per_point(),
-            &event,
+            event,
             self.clipboard.as_mut(),
             &mut self.input_state,
         );

egui_glium/src/painter.rs

@@ -127,9 +127,9 @@ impl Painter {
             struct Vertex {
                 a_pos: [f32; 2],
                 a_tc: [f32; 2],
-                a_srgba: [u8; 4],
+                a_rgba: [f32; 4],
             }
-            implement_vertex!(Vertex, a_pos, a_tc, a_srgba);
+            implement_vertex!(Vertex, a_pos, a_tc, a_rgba);
 
             let vertices: Vec<Vertex> = mesh
                 .vertices
@@ -137,7 +137,7 @@ impl Painter {
                 .map(|v| Vertex {
                     a_pos: [v.pos.x, v.pos.y],
                     a_tc: [v.uv.x, v.uv.y],
-                    a_srgba: v.color.to_array(),
+                    a_rgba: v.color.to_array(),
                 })
                 .collect();
 

egui_glium/src/shader/vertex_100es.glsl

@@ -4,21 +4,10 @@ precision mediump float;
 uniform vec2 u_screen_size;
 attribute vec2 a_pos;
 attribute vec2 a_tc;
-attribute vec4 a_srgba;
-varying vec4 v_rgba;
+attribute vec4 a_rgba; // 0-1
+varying vec4 v_rgba; // 0-1
 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(
@@ -26,7 +15,6 @@ void main() {
                      1.0 - 2.0 * a_pos.y / u_screen_size.y,
                      0.0,
                      1.0);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
-  v_rgba = linear_from_srgba(a_srgba);
+  v_rgba = a_srgba;
   v_tc = a_tc;
 }

egui_glium/src/shader/vertex_120.glsl

@@ -2,30 +2,17 @@
 
 uniform vec2 u_screen_size;
 attribute vec2 a_pos;
-attribute vec4 a_srgba; // 0-255 sRGB
 attribute vec2 a_tc;
-varying vec4 v_rgba;
+attribute vec4 a_rgba; // 0-1
+varying vec4 v_rgba; // 0-1
 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);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
-  v_rgba = linear_from_srgba(a_srgba);
+  v_rgba = a_rgba;
   v_tc = a_tc;
 }

egui_glium/src/shader/vertex_140.glsl

@@ -2,30 +2,17 @@
 
 uniform vec2 u_screen_size;
 in vec2 a_pos;
-in vec4 a_srgba; // 0-255 sRGB
 in vec2 a_tc;
-out vec4 v_rgba;
+in vec4 a_rgba; // 0-1
+out vec4 v_rgba; // 0-1
 out 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, 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);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
-  v_rgba = linear_from_srgba(a_srgba);
+  v_rgba = a_rgba;
   v_tc = a_tc;
 }

egui_glium/src/shader/vertex_300es.glsl

@@ -4,29 +4,16 @@ precision mediump float;
 uniform vec2 u_screen_size;
 attribute vec2 a_pos;
 attribute vec2 a_tc;
-attribute vec4 a_srgba;
-varying vec4 v_rgba;
+attribute vec4 a_rgba; // 0-1
+varying vec4 v_rgba; // 0-1
 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);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
-  v_rgba = linear_from_srgba(a_srgba);
+  v_rgba = a_rgba;
   v_tc = a_tc;
 }