bgiClearCanvasTextShader

Removes the custom text shader from a canvas (reverts to global text shader). Searches g_canvasMap for canvasID. If found, sets canvas.activeTextShader = 0. If canvas not found, function silently does nothing. No return value.

This function resets canvas to use global text shader. Sets activeTextShader to 0 (use global). Canvas uses default text rendering after clearing. Silent failure if canvas doesn't exist. Common pattern: toggle canvas-specific text effects on/off.