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About sharadbirmiwal

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  1. I'm new to vertex shaders. I have written some code that moves vertices based on a constant set by my application. I am moving the vertices (by small distances) after it is multiplied by the view-projection matrix. I am only updatig the <x,y,z> coordinates for every vertex. The effect appears fine but some surfaces of mesh, that should have been hidden behind some other mesh are visible. Could it be because I am not changing the w component? What should "w" be(as a function of x, y, z?), if I am changing it after matrix multiplication? I tried setting w to some fixed constants (1.0, 0.0 etc) for all vertices, but in both cases, all meshes disappear.. The glitch appears as though part of the mesh behind has its Z-buffer value smaller than the one in front. This doesn't happen with all the surfaces and all meshes. Can it be a mesh specific problem? I am writing the shader code in assembly (vs_3_0). Has anyone faced a similar problem? Any suggestions? Thanks (Sorry, but I can't post the entire shader code on a forum..)
  2. sharadbirmiwal

    Simulating a radar in 3D environment

    Once I do a projection transform (using Z buffer), can I read the Z buffer values?
  3. sharadbirmiwal

    Simulating a radar in 3D environment

    Quote:Original post by jyk For the benefit of those of us who aren't up to speed on how radar works (beyond the basics, that is), perhaps you could provide some more information. Are you talking about simulating the details of object-radar interaction, such as occlusion, object profile, material properties, and so on? Well, what I want to do is the basics. Send a pulse(ray?) from the transmitter, and on collision, the point is detected on the receiver (another ray? if receiver.location!=transmitter.location). The signal strength attenuates while travelling in the medium. So if its air, it attenuates as factor 1, if its rain (water), it is factor 2. (btw, attenuation is also a factor of frequency of signal). Rain could be a mesh which is not visible? I'm _assuming_ right now that the reflected signal can be a property of the texture of material. I'm not trying to do an object radar interaction, rather the propogation of pulse. The display of a radar like output wouldn't be a problem. MikeWW, I'm assuming you mean to say that on a separate buffer, I define a new view where the viewing frustrum is defined such. Quote:Next perform a series of ray-traces from the point P to each object within the frustum to check the visibility of that object to P (so you don't detect occluded objects). How do I get a list of all objects within the frustrum? BTW, since radars also have a resolution, and they take the average of pulse energies received from a particular direction (several pulses are sent), I was thinking that I could reduce the number of rays by sending few randomly directed rays in each sector(resolution). Ideas?
  4. For a project, I have to simulate a radar in a 3D environment. I've a (huge)terrain + objects (mostly irregular) scattered in the environment (all meshes). When I think of implementing(a _simulation_) it, only ray tracing comes to mind. But I get stuck with collision detection (the time complexity). One method could be to have simplified models generated (using edge collapses in progressive mesh technique?) for each mesh, and then try ray tracing to improve performance? I've read about the orthogonal projection technique. To add characteristics of a radar image (eg. resolution, colors etc), I could do post projection image processing to get the real thing? Another thing I had in mind was to maybe keep the transmitter and receiver in the environment as separate entities? Can anybody suggest me a better method of going about it/point me to some resources? TIA
  5. sharadbirmiwal

    Terrain generating techniques

    Are there different techniques for terrain rendering? I know the first step is to load/generate the terrain as a triangular mesh, but are there different techniques of rendering which perform differently based on, for example the size of the terrain? Can someone point me to some resources? Thanks Sharad Birmiwal
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