What light property will create a glass pattern on surfaces projected by a flashlight in a game?

The correct choice is cookie, as this term refers to texture patterns that can be projected by lights onto surfaces in a scene, simulating effects such as the appearance of glass or other materials. When a light, such as a flashlight, uses a cookie, it projects a texture that can create intricate patterns, similar to how light passes through or reflects off of texturized glass surfaces. This allows for dynamic and visually interesting environments within the game, enhancing the overall aesthetic and mood.

In contrast, the other options focus on different aspects of lighting. Shadows deal with the absence of light blocked by objects, reflections involve how surfaces can mirror other objects and light, while diffusion relates to the scattering of light for softer edges. None of these aspects create the specific glass pattern effect associated with the use of a cookie.