Switch to a quadratic curve for note brightness based on note velocity

src/deluge/gui/colour/rgb.h

@@ -108,6 +108,13 @@ class RGB {
 		});
 	}
 
+	/**
+	 * @brief Change a color's brightness through a simple
+	 * multiplication operation with a float value
+	 * @return RGB The updated color
+	 */
+	[[nodiscard]] constexpr RGB operator*(float value) const { return RGB(r * value, g * value, b * value); }
+
 	/**
 	 * @brief Dim a colour
 	 *

src/deluge/model/note/note_row.cpp

@@ -1950,7 +1950,7 @@ void NoteRow::renderRow(TimelineView* editorScreen, RGB rowColour, RGB rowTailCo
 
 			RGB& pixel = image[xDisplay];
 
-			// If Note starts somewhere within square, draw the blur colour
+			// If note starts somewhere within square, draw the blur colour
 			if (note && note->pos > squareStartPos) {
 				drewNote = true;
 				pixel = rowBlurColour;
@@ -1959,12 +1959,15 @@ void NoteRow::renderRow(TimelineView* editorScreen, RGB rowColour, RGB rowTailCo
 				}
 			}
 
-			// Or if Note starts exactly on square...
+			// Or if note starts exactly on square...
 			else if (note && note->pos == squareStartPos) {
 				drewNote = true;
-				// this is just colour * (0.25 + 0.75 * velocity) but in fixed point, i.e. it'll go linearly from 0.25
-				// to max brightness with velocity
-				pixel = rowColour.adjustFractional((65 + note->velocity + (note->velocity / 2)) << 8, 255 << 8);
+				float velocity_ratio = static_cast<float>(note->velocity) / 127.f; // velocity range is 1-127
+				float colour_intensity = 0.03 + 0.97 * velocity_ratio * velocity_ratio;
+				// The brightness is reduced as necessary to be proportional to the note velocity.
+				// below .03 (~4/127) it is not visible enough, so we set that as the minimum
+				// A quadratic curve makes the brightness gradient appear more linear.
+				pixel = rowColour * colour_intensity;
 				if (occupancyMask) {
 					occupancyMask[xDisplay] = 64;
 				}