1 files changed, 17 insertions, 1 deletions
diff --git a/tests/manual/rhi/shared/imgui/imgui.frag b/tests/manual/rhi/shared/imgui/imgui.frag
index 51bd615deb..6169dd639f 100644
--- a/tests/manual/rhi/shared/imgui/imgui.frag
+++ b/tests/manual/rhi/shared/imgui/imgui.frag
@@ -8,14 +8,30 @@ layout(location = 0) out vec4 fragColor;
 layout(std140, binding = 0) uniform buf {
     mat4 mvp;
     float opacity;
+    // Windows HDR: set to SDR_white_level_in_nits / 80
+    // macOS/iOS EDR: set to 1.0
+    // No HDR: set to 0.0, will do linear to sRGB at the end then.
+    float hdrWhiteLevelMult;
 };
 
 layout(binding = 1) uniform sampler2D tex;
 
+vec3 linearToSRGB(vec3 color)
+{
+    vec3 S1 = sqrt(color);
+    vec3 S2 = sqrt(S1);
+    vec3 S3 = sqrt(S2);
+    return 0.585122381 * S1 + 0.783140355 * S2 - 0.368262736 * S3;
+}
+
 void main()
 {
     vec4 c = v_color * texture(tex, v_texcoord);
     c.a *= opacity;
-    c.rgb *= c.a;
+    if (hdrWhiteLevelMult > 0.0)
+        c.rgb *= hdrWhiteLevelMult;
+    else
+        c.rgb = linearToSRGB(c.rgb);
+    c.rgb *= c.a; // premultiplied alpha
     fragColor = c;
 }