Backgrounds
Each room can have up to 8 backgrounds. Also it has a background color. All aspects of these backgrounds you can change in a piece of code using the following variables (note that some are arrays that range from 0 to 7, indicating the different backgrounds):
background_color Background color for the room. background_showcolor Whether to clear the window in the background color. background_visible[0..7] Whether the particular background image is visible. background_foreground[0..7] Whether the background is actually a foreground. background_index[0..7] Background image index for the background. background_x[0..7] X position of the background image. background_y[0...7] Y position of the background image. background_width[0...7]* Width of the background image. background_height[0...7]* Height of the background image. background_htiled[0..7] Whether horizontally tiled. background_vtiled[0..7] Whether vertically tiled. background_xscale[0..7] Horizontal scaling factor for the background. (This must be positive; you cannot use a negative value to mirror the background.) background_yscale[0..7] Vertical scaling factor for the background. (This must be positive; you cannot use a negative value to flip the background.) background_hspeed[0..7] Horizontal scrolling speed of the background (pixels per step). background_vspeed[0..7] Vertical scrolling speed of the background (pixels per step). background_blend[0..7] Blending color to use when drawing the background. A value of c_white is the default. Only available in the Pro Edition! background_alpha[0..7] Transparency (alpha) value to use when drawing the background. A value of 1 is the normal setting; a value of 0 is completely transparent.
Contributor: Mark Overmars

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