If you use interpolation for your game’s graphic settings, drawing surfaces can appear blurrier than expected. This is due to graphics being interpolated (smoothed out) when they are drawn to a surface, then being interpolated a second time when the surface is drawn to the main view. There is a simple way to resolve this.

When drawing to a surface, interpolation can be temporarily turned off with texture_set_interpolation() and turned back on when you are finished drawing to the surface. The result is a sharper image when drawing the surface to the main view.

/*** DRAW EVENT ***/
// Set the surface for drawing
surface_set_target(mySurface);

// Turn off interpolation
texture_set_interpolation(false);

// Draw stuff to the surface
draw_sprite(spr_StrongBad, 0, 0);
draw_sprite(spr_HomeStar, 32, 100);

// Turn on interpolation
texture_set_interpolation(true);

// Route drawing back to main view
surface_reset_target();

// Draw the surface to the main view
draw_surface(0, 0);

There!
You should now have a much crisper image when drawing with surfaces!