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Grasshopper

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About Grasshopper

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  1. Havok Physics

    I'm doing some testing of the Havok Physics sdk to see if it meets the requirements of my engine. Does anyone know if a hkpRigidBody can be created with out any shapes added? I'm trying to create a dynamic object with out any collision but I'm getting a crash when I try to create a new  hkpRigidBody with bodyCinfo.m_shape set to NULL. Seems strange that such a popular physics sdk wouldn't support such a basic feature.    
  2. Direct3d slowing down other threads

    Thanks for the replies. None of these things seem to be the case as far as I can tell. Back to banging my head against the wall.
  3. I've got a MFC program that does all the rendering in the main tread and uses a seperate thread for physics. For some reason when I comment out the main render update function my physics thread runs faster even though no communication is happening between the two threads. If I replace the render update function with code that wastes time in a while loop the physics thread also runs faster. The Direct3D device is being created with D3D11_CREATE_DEVICE_SINGLETHREADED. Does anyone what might be going on here?
  4. I want to write one pixel depth value to the z-buffer but test against another value with a offset added. This is to overcome objects that are z fighting against the terrain. I want to write the normal depth value to the z-buffer but have a offset added when testing agains the terrain z values. Is there any easy way to do this?
  5. I'm trying to tessellate a quad for some displacement mapping. I also need to do some edge detection in a geometry shader once my quad has been tessellated but I can't seem to find a way to generate any adjacency information in the domain shader. Does anyone know how I might go about doing this? If I could figure out how the SV_DomainLocation coordinates are generated based on the tessellation factors are generated then I might be able to predict where the neighbor vertices would be.
  6. This has been enlightening so far. I'm guessing that with exponential attenuation (e^-a*dis) for say fog this would be applied to the distance from light to object(d1) and the distance from object to camera (d2). So the final attenuation would be (e^-a*(d1+d2)) due to the absorption/scattering of light?
  7. A light source at distance d1 from a object attenuates at 1/(d1*d1). If the point at which the light hits a object is at distance d2 from the camera shouldn't the light also attenuate by 1/(d2*d2) as it travels from the reflection point back to the camera? I know sonars works this way but I don't really see lighting calculations done like this. Anyone know why?
  8. I'm in the processes of testing my software with the nvidia nvision 3d glasses on a 120Hz monitor. I notice that the screen gets a lot darker once the 3d effect kicks in. Does anyone know what the best way to compensate for this effect is? Should I just scale the final pixel color by a fixed amount? Show this be done before or after gamma correction?
  9. Thinking of applying for a game development job.

    Can someone working in the game industry tell me if vacation time usually goes up with job experience. What kind of time off would a senior programmer get?
  10. I'm thinking of applying for a programming position at a east cost company called Other Ocean. Does any one here have any experience with this company? I'm wondering about things like the work environment and usually hours of work. I've never worked for a game development studio but my current job uses mostly the same skill set. Another issue I'm concerned about is vacation time. At my current job I'm getting three weeks off a year plus a week during Christmass. What kind off vacation time am I looking at in the game industry?
  11. float Perlin::perlin_noise_3D(float vec[3]) { float result = 0.0f; vec[0]*=_frequency; vec[1]*=_frequency; vec[2]*=_frequency; float divider = 0; float scale = 1; for (int i=0;i<_octaves;i++) { result += noise3(vec)*scale; vec[0] *= 2.0f; vec[1] *= 2.0f; vec[2] *= 2.0f; divider += scale; scale *= 0.5f; } return _amplitude*pow(result/divider,3.0f); } Are these the right changes? The effect seems a bit better. Are there any articles or samples that you could link me to that might increase my understanding of all this?
  12. Has any one out there tried using perlin noise to generate wind turbulence? I'm trying to create an effect similar to the turbulence field that can be generated in 3DS Max using the Wind Space Warp. Here is my current approach to updating each particle in the turbulence field. // perlin function float Perlin::get(float x,float y,float z) { float result = 0.0f; float amp = _amplitude; x *=_frequency; y *=_frequency; z *=_frequency; for (int i=0;i<_octaves;i++) { result = noise3(x,y,z)*amp; x *= 2.0f; y *= 2.0f; z *= 2.0f; amp *=0.5f; } return result; } // particle update turbulenceVel.x =_perlin.get(particle->pos.x,particle->pos.y,particle->pos.z); turbulenceVel.y =_perlin.get(particle->pos.x+100,particle->pos.y,particle->pos.z); turbulenceVel.z =_perlin.get(particle->pos.x,particle->pos.y,particle->pos.z+100); particle->pos += windVel*timeStep + turbulenceVec*timeStep; The problem that I'm having is that no matter how much I fool around with the amplitude, octaves or frequency of the perlin noise function I can't seem to get a nice turbulence effect. The result always seems either too wavy or too jittery. Does anyone have any suggestions on how I can improve this routine?
  13. Thanks for the responces. Looks like I'll have a great starting point.
  14. I'm working on a project that requires the simulation of underwater vehicles and objects. What I want to do is describe the quadratic and linear drag (c1*v^2 + c2*v) forces on objects using primitive shapes like ellipses and rectangles. Is there any method I could use to come up with these drag coefficients for simple shapes? Even if I had to use look up tables that would be fine but and can't seem to find any information anywhere.
  15. I think Omid Ghavami just told me what i wanted to hear. Thanks for the responces.
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