[client] egl: make the bgr_bgra filter generic for 24-bit formats

client/renderers/EGL/shader/convert_24bit.frag

@@ -0,0 +1,32 @@
+#version 300 es
+#extension GL_OES_EGL_image_external_essl3 : enable
+
+precision highp float;
+
+in  vec2  fragCoord;
+out vec4  fragColor;
+
+uniform sampler2D sampler1;
+uniform vec2      outputSize;
+
+void main()
+{
+  uvec2 inputSize = uvec2(textureSize(sampler1, 0));
+  uvec2 outputPos = uvec2(fragCoord * outputSize);
+
+  uint fst = outputPos.x * 3u / 4u;
+  vec4 color_0 = texelFetch(sampler1, ivec2(fst, outputPos.y), 0);
+
+  uint snd = (outputPos.x * 3u + 1u) / 4u;
+  vec4 color_1 = texelFetch(sampler1, ivec2(snd, outputPos.y), 0);
+
+  uint trd = (outputPos.x * 3u + 2u) / 4u;
+  vec4 color_2 = texelFetch(sampler1, ivec2(trd, outputPos.y), 0);
+
+  OUTPUT = vec4(
+    color_0.barg[outputPos.x % 4u],
+    color_1.gbar[outputPos.x % 4u],
+    color_2.rgba[outputPos.x % 4u],
+    1.0
+  );
+}