NAME

rendertarget_noclear - Enable / Disable clearing a rendertarget before a renderpass.

SYNOPSIS

success
rendertarget_noclear( vid, noclear )

DESCRIPTION

By default, each pass for a rendertarget begins by clearing the buffer that will be drawn to. This may waste memory bandwidth if we know that the entire rendertarget will be populated with the objects that are to be drawn. rendertarget_noclear is used to change this behavior by setting a true value to a vid that is connected to a rendertarget.

NOTES

1: Setting WORLDID as vid will change the clear behavior for the standard output rendertarget.
2: If the background is not actually covered by valid VID s, you will leave trails of previous frames behind, as in the MAIN example below.

EXAMPLE

function rendertarget_noclear0()
      rendertarget_noclear(WORLDID, true);
      a = color_surface(64, 64, 255, 0, 0, 0);
      show_image(a);
      move_image(a, 128, 128, 10);
end

MISUSE

function rendertarget_noclear0()
      rendertarget_noclear(BADID, "potatoe");
end