![]() There were several examples where triangles and squares had been used together. Many of the examples were quite creative, and I never would have been able to think them up on my own. I saw several examples of tessellation in my daughter’s geometry book last semester. I think it helps my eyes and my mind wake up in the morning. ![]() I have my kitchen tiled like this, and to me, it really brightens up the place. It’s sort of an optical illusion, yet it is so simple at the same time. Staring at them for any length of time will make your eyes do strange things. I like the black and white squares that have been tilted to look like diamonds and have been alternated to play with your eyes. May 19, - While it would be cool to have a unique tiling tessellation, I actually prefer the old-fashioned kind found in the cafes and diners of years past. Three of the lizards are arranged so that they touch noses in the center, while the other three touch tails. We also have a lizard tessellation puzzle. Two shades of brown were used, and a light brown elephant would lock trunks with a dark brown one, so my daughter always knew which ones to fit together. She had a lot of fun learning how they fit together, and they looked really cool once they were totally finished. You can also control the frequency of the noise function, the terrain height, and how many noise octaves are used to generate the terrain.I got my daughter a couple of wooden jigsaw puzzles featuring animal tessellations. This mode is typically much slower, since patches in the distance are typically very over-tessellated. If "auto LOD" is disabled, you can directly control the tessellation factors using the two sliders. If "auto LOD" mode is enabled, the tessellation level is calculated to try and maintain a constant screen-space triangle size, which is controlled by the "triangle size" slider. Each quality level up doubles the resolution in each dimension (4 times the number of triangles). There are several different quality settings, which vary the number of terrain patches, and how large each patch is. The Tweakbar has several options and sliders to control various parameters. The geometry shader method is usually slower on current hardware, and only calculates a flat surface normal.įinally, the terrain color is calculated in the fragment shader, based on the height and normal. Surface normals for the terrain can be calculated in two ways: either by evaluating the terrain function at two additional neighboring points in the tessellation evaluation shader (if the "smooth normals" option is enabled), or per-triangle using the geometry shader (if "smooth normals" is disabled). It uses the derivatives of the noise function to weight the noise octaves. The noise function is used is based on an advanced perlin noise article by Inigo Quilez (see link below). Using hardware linear interpolation does not look as good, and has stepping artifacts at low frequencies due to the limited hardware precision (9 bits sub-texel). ![]() The GLSL textureGather() function is used to read the neighboring texels in a single pass, so that custom smooth interpolation can be performed. Procedural noise is calculated based on a small 2D texture containing random values. The terrain height is calculated procedurally for each generated vertex in the tessellation evaluation shader. (as described in NVIDIA's DirectX 11 terrain tessellation sample, see link below).Ĭulling is performed by testing the bounding sphere of the patch against the view frustum planes. Level of detail is calculated based on the projected screen size of a sphere fitted to each patch edge Level of detail (determining the tessellation level) and view frustum culling are performed in the tessellationĬontrol shader. The actual patch origin positions are then calculated from the gl_InstanceID in the vertex This means the whole terrain is rendered with a single draw call. The patches are rendered using instancing, using the glDrawArraysInstanced() function with a dummy vertex buffer. Is the limit for the current tessellation hardware). The code renders the terrain as a grid of patches, each of which can generate a grid of up to 64 x 64 triangles (this It is not intended to show the optimal way of rendering terrain, but more to serve as a testbed for experimenting with tessellation shaders and different terrain heightfield functions. This sample demonstrates how to render a procedural terrain using OpenGL tessellation shaders, including automatic level of detail and culling.
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