You may try to play with rotation of thin long model rendered inside textdraw.
PHP код:
new Text:textdraw = TextDrawCreate(320.0, 240.0, "_");
TextDrawFont(textdraw, TEXT_DRAW_FONT_MODEL_PREVIEW);
TextDrawUseBox(textdraw, 1);
TextDrawBoxColor(textdraw, 0x000000FF);
TextDrawTextSize(textdraw, 40.0, 40.0);
TextDrawSetPreviewModel(textdraw, 1212); // Replace 1212 with something thin and long
TextDrawSetPreviewRot(textdraw, -10.0, 0.0, -20.0, 1.0); // Change these values to rotate model
Some thin long models:
http://*******/7fd2q6 ("cane gun")
http://*******/h8s30a ("pool cue")
By the way, SA-MP can change rendered model color but in different way. I don't know is it possible to make models white, but I'm sure you can make them black.