perf: add early-out for transparent overlay in blendColors

simonklee · simonklee · commit e12f72e64810 · 2026-01-12T07:01:06.000+01:00
Skip pow and vector math when overlay alpha is fully transparent,
returning text color directly. The common case for text backgrounds.
diff --git a/packages/core/src/zig/buffer.zig b/packages/core/src/zig/buffer.zig
@@ -97,6 +97,9 @@ fn blendColors(overlay: RGBA, text: RGBA) RGBA {
     if (overlay[3] == 1.0) {
         return overlay;
     }
+    if (overlay[3] == 0.0) {
+        return text;
+    }
 
     const alpha = overlay[3];
     var perceptualAlpha: f32 = undefined;

Original file line number	Diff line number	Diff line change
`@@ -97,6 +97,9 @@ fn blendColors(overlay: RGBA, text: RGBA) RGBA {`
`97`	`97`	`if (overlay[3] == 1.0) {`
`98`	`98`	`return overlay;`
`99`	`99`	`}`
	`100`	`+ if (overlay[3] == 0.0) {`
	`101`	`+ return text;`
	`102`	`+ }`
`100`	`103`
`101`	`104`	`const alpha = overlay[3];`
`102`	`105`	`var perceptualAlpha: f32 = undefined;`