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  • Unity3d: calculate the result of a transform without modifying transform object itself

    - by Heisenbug
    I'm in the following situation: I need to move an object in some way, basically rotating it around its parent local position, or translating it in its parent local space (I know how to do this). The amount of rotation and translation is know at runtime (it depends on several factors, the speed of the object, enviroment factors, etc..). The problem is the following: I can perform this transformation only if the result position of the transformed object fit some criterias. An example could be this: the distance between the position before and after the transformation must be less than a given threshold. (Actually the conditions could be several and more complex) The problem is that if I use Transform.Rotate and Transform.Translate methods of my GameObject, I will loose the original Transform values. I think I can't copy the original Transform using instantiate for performance issues. How can I perform such a task? I think I have more or less 2 possibilities: First Don't modify the GameObject position through Transform. Calculate which will be the position after the transform. If the position is legal, modify transform through Translate and Rotate methods Second Store the original transform someway. Transform the object using Translate and Rotate. If the transformed position is illegal, restore the original one.

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  • Basic tutorial/introduction for 3d matrices, idealy in c++, without openGl or directX

    - by René Nyffenegger
    I am wondering if there is a simple tutorial that covers the basics of how to initialize rotation, translation and projection matrices, and how to multiply them, and how to get the screen coordinates afterwards for a 3d point. Idealy, the tutorial comes with compilable code and is not dependent on any 3rd party library. Searching the internet, I found lots of tutorials, so this is not the problem. Yet, it seemed all of these either covered openGl or directX, or they were theoretical in nature.

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  • Calculating 3D camera positions from a video

    - by Geotarget
    I need to calculate the 3D camera position and rotation for each frame in a given video. This is typically used for motion-tracking, and to insert 3D objects into a video. I'm currently using VideoTrace to calculate this for me, and I'm getting the data exported as a 3DS Maxscript file. However when I try to use the 3D camera rotations, I'm getting strange errors in my 3D calculations, as if there is an error with the 3x3 rotation matrices. Can you spot any error with the data itself? Or is it my other calculations that are erroneous? frame 1 rotation=(matrix3[-0.011938, 0.756018, -0.654442][-0.382040, -0.608284, -0.695727][-0.924068, 0.241718, 0.296091][0, 0, 0]).rotationpart position=[-0.767177, 0.308723, -0.232722] fov=57.352135 frame 2 rotation=(matrix3[-0.460922, -0.726580, -0.509541][-0.200163, 0.644491, -0.737947][ 0.864572, -0.238145, -0.442495][0, 0, 0]).rotationpart position=[-0.856630, 0.198654, -0.243853] fov=57.352135

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  • How do I have to take into account the direction in which the camera is facing when creating a first person strafe (left/right) movement

    - by Chris
    This is the code I am currently using, and it works great, except for the strafe always causes the camera to move along the X axis which is not relative to the direction in which the camera is actually facing. As you can see currently only the x location is updated: [delta * -1, 0, 0] How should I take into account the direction in which the camera is facing (I have the camera's target x,y,z) when creating a first person strafe (left/right) movement? case 'a': var eyeOriginal = g_eye; var targetOriginal = g_target; var viewEye = g_math.subVector(g_eye, g_target); var viewTarget = g_math.subVector(g_target, g_eye); viewEye = g_math.addVector([delta * -1, 0, 0], viewEye); viewTarget = g_math.addVector([delta * -1, 0, 0], viewTarget); g_eye = g_math.addVector(viewEye, targetOriginal); g_target = g_math.addVector(viewTarget, eyeOriginal); break; case 'd': var eyeOriginal = g_eye; var targetOriginal = g_target; var viewEye = g_math.subVector(g_eye, g_target); var viewTarget = g_math.subVector(g_target, g_eye); viewEye = g_math.addVector([delta, 0, 0], viewEye); viewTarget = g_math.addVector([delta, 0, 0], viewTarget); g_eye = g_math.addVector(viewEye, targetOriginal); g_target = g_math.addVector(viewTarget, eyeOriginal); break;

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  • Calculating the position of an object with regards to current position using OpenGL like matrices

    - by spartan2417
    i have a 1st person camera that collides with walls, i also have a small sphere in front of my camera denoted by the camera position plus the distance ahead. I cannot get the postion of the sphere but i have the position of my camera. e.g. i need to find the position of the point or at the very least find away of calculating the position using the camera positions. code: static Float P_z = 0; P_z = -15; PushMatrix(); LoadMatrix(&Inv); Material(SCEGU_AMBIENT, 0x00000066); TranslateXYZ(0,0,P_z); ScaleXYZ(0.1f,0.1f,0.1f); pointer.Render(); PopMatrix(); where Inv is the camera positions (Inv.w.x,Inv.w.z), pointer is the sphere.

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  • How do I create a camera?

    - by Morphex
    I am trying to create a generic camera class for a game engine, which works for different types of cameras (Orbital, GDoF, FPS), but I have no idea how to go about it. I have read about quaternions and matrices, but I do not understand how to implement it. Particularly, it seems you need "Up", "Forward" and "Right" vectors, a Quaternion for rotations, and View and Projection matrices. For example, an FPS camera only rotates around the World Y and the Right Axis of the camera; the 6DoF rotates always around its own axis, and the orbital is just translating for a set distance and making it look always at a fixed target point. The concepts are there; implementing this is not trivial for me. SharpDX seems to have has already Matrices and Quaternions implemented, but I don't know how to use them to create a camera. Can anyone point me on what am I missing, what I got wrong? I would really enjoy if you could give a tutorial, some piece of code, or just plain explanation of the concepts.

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  • How to do directional per fragment lighting in world space?

    - by user
    I am attempting to create a GLSL shader for simple, per-fragment directional light. So far, after following many tutorials, I have continually ran into the issue: my light is specified in world coordinates, however, the shader treats the light's position as being in eye space, thus, the light direction changes when I move the camera. My question is, how to I transform a directional light position such as (50, 50, 50, 0) into eye space, or, would doing things this way be the incorrect approach to the problem?

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  • Inverse projection: question about w coordinate

    - by fayeWilly
    I have to perform in shader an inverse projection from a u/v of a render target. What I do is: Get NDC as 2*(u,v,depth) - 1 Then world space as tmp = (P*V)^-1 * (NDC,1.0); world space = tmp/tmp.w; This apparently works, but I am confused about the w division there. Why this work? Shouldn't be a multiplication by a w somewhere (as in the "forward" pipeline there is the perpsective division?) Thank you, Faye

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  • How do I create a bounding frustrum from a view & projection matrix?

    - by Narf the Mouse
    Given a left-handed Projection matrix, a left-handed View matrix, a ViewProj matrix of View * Projection - How do I create a bounding Frustum comprised of near, far, left, right and top, bottom planes? The only example I could find on Google (Tutorial 16: Frustum Culling) seems to not work; for example, if the math is used as given, the near-plane's distance is a negative. This places the near-plane behind the camera...

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  • Rotating a child shape relative to its parent's orientation

    - by user1423893
    When rotating a shape using a quaternion value I also wish rotate its child shape. The parent and child shapes both start with different orientations but their relative orientations should always be the same. How can I use the difference between the previous and current quaternions of the parent shape in order to transform the child segment and rotate it relative to its parent shape? public Quaternion Orientation { get { return entity.Orientation; } set { Quaternion previousValue = entity.Orientation; entity.Orientation = value; // Use the difference between the quaternion values to update child orientation } }

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  • HLSL What you get when you subtract world position from InvertViewProjection.Transform?

    - by cubrman
    In one of NVIDIA's Vertex shaders (the metal one) I found the following code: // transform object normals, tangents, & binormals to world-space: float4x4 WorldITXf : WorldInverseTranspose < string UIWidget="None"; >; // provide tranform from "view" or "eye" coords back to world-space: float4x4 ViewIXf : ViewInverse < string UIWidget="None"; >; ... float4 Po = float4(IN.Position.xyz,1); // homogeneous location coordinates float4 Pw = mul(Po,WorldXf); // convert to "world" space OUT.WorldView = normalize(ViewIXf[3].xyz - Pw.xyz); The term OUT.WorldView is subsequently used in a Pixel Shader to compute lighting: float3 Ln = normalize(IN.LightVec.xyz); float3 Nn = normalize(IN.WorldNormal); float3 Vn = normalize(IN.WorldView); float3 Hn = normalize(Vn + Ln); float4 litV = lit(dot(Ln,Nn),dot(Hn,Nn),SpecExpon); DiffuseContrib = litV.y * Kd * LightColor + AmbiColor; SpecularContrib = litV.z * LightColor; Can anyone tell me what exactly is WorldView here? And why do they add it to the normal?

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  • Premultiplying matrices with Perspective destroys them

    - by Shadows In Rain
    If I apply world_to_camera, perspective and camera_to_screen to my mesh, everything is okay. But if I premultiply given matrices (i.e. transform = world_to_camera * perpective * camera_to_screen) before applying, then it seems like only perspective has effect. If it is important... My 3d framework was written from scratch (test project for job interview). But it works flawlessly, or at least I think so. So, question. This is expected behaviour, or my implementation is wrong?

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  • Why do we move the world instead of the camera

    - by sharethis
    I heard that in an OpenGL game what we do to let the player move is not to move the camera but to move the whole world around. For example here is an extract of this tutorial: http://open.gl/transformations In real life you're used to moving the camera to alter the view of a certain scene, in OpenGL it's the other way around. The camera in OpenGL cannot move and is defined to be located at (0,0,0) facing the negative Z direction. That means that instead of moving and rotating the camera, the world is moved and rotated around the camera to construct the appropriate view. Why do we do that?

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  • Problems with 3D transformation - (SharpDX)

    - by Morphex
    First of all , I have been trying to get this right for a couple of day already, I have read so much info and still fail miserably to understand this. So I am going to tell you that even though I have done fairly amount of research myself, I failed to implement it. I must say miserably I am trying to create a generic camera class for a game engine of sorts - for research purposes only - the thing is I have no idea how to go about it. I have read about quaternions and matrices, but when it comes to the actual implementation I suck at it. Sharpdx has already Matrices and QUaternions implemented. SO no big deal on the map behind it. How in the world would I go about creating a camera? I have seen so many camera examples and still can't make one that works as expected. I would like to implement diferent types too (Orbital, 6DoF, FPS). So what is need for a camera? UP, Forward and Right vectors I read they are needed, also a quaternion for rotations, and View and Projection matrices. I understand that a FPS camera for instance only rotates around the World Y and the Right Axis of the camera. the 6DoF rotates always around their own axis, and the orbital is just translating for set distance and making it look always at a fixed target point. The concepts are there, now implementing this is not trivial for me. Can anyone point me on what am I missing, what I got wrong? I would really enjoy if you could give a tutorial, some piece of code, or just plain explanation of the concepts. Thank you for readin, a frustrated coder.

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  • How can I implement smooth rotation from one direction to another?

    - by user1759052
    I'm having a problem with animating rotations with 1Matrix.CreateRotationY() with my basic 3D game. Based on where you click the mouse, I want the 3D object to rotate to that direction and then move. I am using this to determine the target direction: float rot = (float)(Math.Atan2(X, Z)); It gives me the correct value, but I am not sure how to handle the rotation animation from current direction to new direction. I've tried a few things, but to no avail. Do you guys know of any good ways of solving this issue?

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  • Ray-Box Intersection during Scene traversal with matrix transforms

    - by Myx
    Hello: There are a few ways that I'm testing my ray-box intersections: Using the ComputeIntersectionBox(...) method, that takes a ray and a box as arguments and computes the closest intersection of the ray and the box. This method works by forming a plane with each of the faces of the box and finding an intersection with each of the planes. Once an intersection is found, a check is made whether or not the point is on the surface of the box by checking that the intersection point is between the corner points. When I look at rays after running this algorithm on two different boxes, I obtain the correct intersections. Using ComputeIntersectionScene(...) method without using the matrix transformations on a scene that has two spheres, a dodecahedron (a triangular mesh), and two boxes. ComputeIntersectionScene(...) recursively traverses all of the nodes of the scene graph and computes the closest intersection with the given ray. This test in particular does not apply any transformations that parent nodes may have that also need to be applied to their children. With this test, I also obtain the correct intersections. Using ComputeIntersectionScene(...) method WITH the matrix transformations. This test works like the one above except that before finding an intersection between the ray and a node in the scene, the ray is transformed into the node's coordinate frame using the inverse of the node's transformation matrix and after the intersection has been computed, this intersection is transformed back into the world coordinates by applying the transformation matrix to the intersection point. When testing with the third method on the same scene file as described in 2, testing with 4 rays (thus one ray intersects the one sphere, one ray the the other sphere, one ray one box, and one ray the other box), only the two spheres get intersected and the two boxes do not get intersections. When I debug looking into my ComputeIntersectionBox(...) method, it actually tells me that the ray intersects every plane on the box but each intersection point does not lie on the box. This seems to be strange behavior, since when using test 2 without transformations, I obtain the correct box intersections (thus, I believe my ray-box intersection to be correct) and when using test 3 WITH transformations, I obtain the correct sphere intersections (thus, I believe my transformed ray should be OK). Any suggestions where I could be going wrong? Thank you in advance.

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  • submatrix from a matrix

    - by Grv
    A matrix is of size n*n and it consists only 0 and 1 find the largest submatrix that consists of 1's only eg 10010 11100 11001 11110 largest sub matrix will be of 3*2 from row 2 to row 4 please answer with best space and time complexity

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  • I want to create adjacency matrix using python

    - by A A
    I have very large data set it is almost 450000 lines and two rows, i want to compute adjacency matrix using python, because previously i have tried to do it in matlab, and it shows memory error because of large data values. my data values also start from 100 and goes upto 450000, Anyone can help me in this issue, as i am new to python. I have to first import the file into python using excel sheet or notepad and then compute the adjacency matrix

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  • OpenGL Projection matrix won't allow displaying anything

    - by user272973
    I'm trying to get some basic OpenGL-ES with Shaders to run on the iPhone, based on some examples. For some reason my projection matrix refuses to result in something on the screen. It feels like a clipping plane is set very near but that contradicts with the values I supply. If I render the same scene with an Orthogonal projection matrix I see my object just no perspective obviously. Here's the code that generates the projection matrix: esPerspective(&proj, 45.f, 768.0/1024.0, 1.f, 10000.f); void esPerspective(ESMatrix *result, float fovy, float aspect, float nearZ, float farZ) { float frustumW, frustumH; frustumH = tanf( fovy / 360.0f * PI ) * nearZ; frustumW = frustumH * aspect; esFrustum( result, -frustumW, frustumW, -frustumH, frustumH, nearZ, farZ ); } void esFrustum(ESMatrix *result, float left, float right, float bottom, float top, float nearZ, float farZ) { float deltaX = right - left; float deltaY = top - bottom; float deltaZ = farZ - nearZ; ESMatrix frust; if ( (nearZ <= 0.0f) || (farZ <= 0.0f) || (deltaX <= 0.0f) || (deltaY <= 0.0f) || (deltaZ <= 0.0f) ) return; frust.m[0][0] = 2.0f * nearZ / deltaX; frust.m[0][1] = frust.m[0][2] = frust.m[0][3] = 0.0f; frust.m[1][1] = 2.0f * nearZ / deltaY; frust.m[1][0] = frust.m[1][2] = frust.m[1][3] = 0.0f; frust.m[2][0] = (right + left) / deltaX; frust.m[2][1] = (top + bottom) / deltaY; frust.m[2][2] = -(nearZ + farZ) / deltaZ; frust.m[2][3] = -1.0f; frust.m[3][2] = -2.0f * nearZ * farZ / deltaZ; frust.m[3][0] = frust.m[3][1] = frust.m[3][3] = 0.0f; esMatrixMultiply(result, &frust, result); } My projection matrix comes out as: [3.21, 0, 0, 0] [0, 2.41, 0, 0] [0, 0, -1, -1] [0, 0, -2, 0] Even if I manually set the [3][3] cell to 1 I still don't see anything. Any ideas?

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  • Gnuplot - splot matrix csv data

    - by Jakub Czaplicki
    How can I plot (a 3D plot) a matrix in Gnuplot having such data structure. I cannot find a way to use the first row and column as a x and y ticks (or to ignore them) ,5,6,7,8 1,-6.20,-6.35,-6.59,-6.02 2,-6.39,-6.52,-6.31,-6.00 3,-6.36,-6.48,-6.15,-5.90 4,-5.79,-5.91,-5.87,-5.46 Is the splot 'data.csv' matrix the correct parameter to use ?

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  • Matrix multiplication in java

    - by Chapax
    Hi, I wanted to do matrix multiplication in Java, and the speed needs to be very good. I was thinking of calling R through java to achieve this. I had a couple of Qs though: Is calling R using Java a good idea? If yes, are there any code samples that can be shared? What are the other ways that can be considered to do matrix multiplication in Java? Many thanks. --Chapax

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  • Adding Names to columns in a matrix

    - by Jeff
    I have my matrix I have created, a pic found here. http://s816.photobucket.com/albums/zz83/gavakie/?action=view&current=matrix.jpg The first three column what whats being grouped by but I can had the names of those columns, how can I do that in Reporting Services?

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  • Traspose matrix-style table to 3 columns in Excel

    - by polarbear2k
    I have a matrix-style table in excel where B1:Z1 are column headings and A2:A99 are row headings. I would like to convert this table to a 3 column table (column heading, row heading, cell value). It does not matter in what order the new table is. A B C D A B C A B C 1 H1 H2 H3 1 H1 R1 V1 1 H1 R1 V1 2 R1 V1 V2 V3 => 2 H1 R2 V4 or 2 H2 R1 V2 3 R2 V4 V5 V6 3 H1 R3 V7 3 H3 R1 V3 4 R3 V7 V8 V9 4 H2 R1 V2 4 H1 R2 V4 5 H2 R2 V5 5 H2 R2 V5 6 H2 R3 V8 6 H3 R2 V6 7 H3 R1 V3 7 H1 R3 V7 8 H3 R2 V6 8 H2 R3 V8 9 H3 R3 V9 9 H3 R3 V8 I've been playing around with the OFFSET function to create the whole table but I feel like a combination of TRANSPOSE and V/HLOOKUP is required. Thanks

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  • Create a term-document matrix from files

    - by Joe
    I have a set of files from example001.txt to example100.txt. Each file contains a list of keywords from a superset (the superset is available if we want it). So example001.txt might contain apple banana ... otherfruit I'd like to be able to process these files and produce something akin to a matrix so there is the list of examples* on the top row, the fruit down the side, and a '1' in a column if the fruit is in the file. An example might be... x example1 example2 example3 Apple 1 1 0 Babana 0 1 0 Coconut 0 1 1 Any idea how I might build some sort of command-line magic to put this together? I'm on OSX and happy with perl or python...

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