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FlightGear Newsletter July 2012: Difference between revisions
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→Procedural texturing
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Usually, textures of models or scenery are prepared in advance, then loaded and rendered by Flightgear. Procedural texturing is the idea to compute the texture to be rendered inside the fragment shader rather than using a pre-defined texture. The main disadvantage of the scheme is its higher framerate cost. However, unlike pre-defined textures which show repetition ('tiling') over distances much larger than the texture size, a computation inside the fragment shader can evaluate a function which does not show tiling and use this as basis for the final texture. At the same time, details like a terrain heightmap or color variations at any size scale can be generated. | Usually, textures of models or scenery are prepared in advance, then loaded and rendered by Flightgear. Procedural texturing is the idea to compute the texture to be rendered inside the fragment shader rather than using a pre-defined texture. The main disadvantage of the scheme is its higher framerate cost. However, unlike pre-defined textures which show repetition ('tiling') over distances much larger than the texture size, a computation inside the fragment shader can evaluate a function which does not show tiling and use this as basis for the final texture. At the same time, details like a terrain heightmap or color variations at any size scale can be generated. | ||
Since the textures are computed dynamically, it is also possible to let the terrain elevation or slope influence the result (as demonstrated by the existing | Since the textures are computed dynamically, it is also possible to let the terrain elevation or slope influence the result (as demonstrated by the existing snow and transition effect shaders). Using procedural texturing in the terrain shader to mix several textures and add environment effects allows to render the Flightgear terrain in unprecedented visual detail. The dynamical texture generation hides the seams between different landclasses, can generate terrain roughness at a high level of detail, can easily add the effect of light reflection from water puddles in wet terrain and can be used for extremely high resolution texturing of airport landclasses. | ||