NAME

image_mipmap - Forcetoggle image mipmap storage

SYNOPSIS

nil
image_mipmap( vid, state )

DESCRIPTION

Mipmapping is the common procedure of generating multiple versions of the same image (typically at lower resolutions for each "level") and letting the rendering subsystem determine which version is the most suitable for the rendering operation at hand. This usually saves on memory bandwidth at the cost of approximately a third more memory consumption. This function enforces a certain mipmap state for a video object. Some filtering methods, FILTER_TRILINEAR in particular, relies on access to lower mipmap levels.

NOTES

1: This is a no-operation in memory conservative mode.
2: The default mipmap state for all objects is determined at compile time ( ARCAN_VIDEO_DEFAULT_MIPMAP_STATE ), with hardcoded mipmap disable defaults for frameservers and for rendertarget storage.
3: The engine does not currently support manually generated mipmaps. These can be useful in some contexts, particularly when dealing with texture compression or when optimizing memory use through pre-pass analysis of visibility with color-coded mipmap levels.
4: This state transformation is costly with non-trivially determined benefits. In order to reliably switch open GL backend state, a new GL store needs to be created, thus the raw texture data is copied and uploaded again.

EXAMPLE

function image_mipmap0()
      icon = load_image("test.png");
      props = image_surface_properties(icon);
      icon2 = null_surface(props.width, props.height);
      icon2 = image_sharestorage(icon, icon2);
      show_image({icon, icon2});
      resize_image(icon, props.width * 0.5, props.height * 0.5);
      resize_image(icon2, props.width * 0.5, props.height * 0.5);
      move_image(icon2, props.width, 0);
      image_mipmap(icon2, false);
      image_mipmap(icon, true);
end

MISUSE