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  • Hashing 3D position into 2D position

    - by notabene
    I am doing volumetric raycasting and curently working on depth jitter. I have 3D position on ray and want to sample 2D noise texture to jitter the depth. Function for converting (or hashing) 3D position to 2D have to produce absolutely different numbers for a little changes (especialy because i am sampling in texture space so sample values differs very very little) and have to be "shader-wise" - so forget about branches, cycles etc. I'm looking forward for yours nice and fast solutions.

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  • Great Circle & Ray intersection

    - by Karl T
    I have a Latitude, Longitude, and a direction of travel in degrees true north. I would like to calculate if I will intersect a line defined by two more Lat/Lon points. I figure the two points defining the line would create my great circle and my location and azimuth would define my ray (or possibly a small circle). Any ideas?

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  • Literature and Tutorials for Writing a Ray Tracer

    - by grrussel
    I am interested in finding recommendations on books on writing a raytracer, simple and clear implementations of ray tracing that can be seen on the web, and online resources on introductory raytracing. Ideally, the approach would be incremental and tutorial in style, and explain both the programming techniques and underyling mathematics, starting from the basics.

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  • How do I play HD video without stuttering?

    - by hugocreal
    Hello All, I want play a Blu Ray Video from my hard drive with Boxee, but it chokes all the time, i try play with others video players but is the same. I think that is a 10gb .mkv file with 10Gb. Stuttering video with VLC , mplayer, and the default video player on ubuntu... I read in many Forums just can´t put this to work. Any idea? thanks. Ubuntu 10.10, My PC specs: Single Core 2Ghz ATI HD 4350 (i have installed the drivers from "Hardware Drivers"), 2G Memory

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  • How do I play HD video without it stuttering?

    - by hugocreal
    Hello All, I want play a Blu Ray Video from my hard drive with Boxee, but it chokes all the time. I've tried to play it with others video players but it is the same. I think that is a 10gb .mkv file with 10Gb. Stuttering video with VLC , mplayer, and the default video player on ubuntu. I read in many Forums just can´t put this to work. Any idea? thanks. Ubuntu 10.10, My PC specs: Single Core 2Ghz ATI HD 4350 (i have installed the drivers from "Hardware Drivers"), 2G Memory *EDIT: Problem solved, this weekend had buy a motherboard and a processor DualCore 2.5Ghz, no more stuttering. thanks alot for your help.

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  • OpenGL ES 2.0 gluUnProject

    - by secheung
    I've spent more time than I should trying to get my ray picking program working. I'm pretty convinced my math is solid with respect to line plane intersection, but I believe the problem lies with the changing of the mouse screen touch into 3D world space. Heres my code: public void passTouchEvents(MotionEvent e){ int[] viewport = {0,0,viewportWidth,viewportHeight}; float x = e.getX(), y = viewportHeight - e.getY(); float[] pos1 = new float[4]; float[] pos2 = new float[4]; GLU.gluUnProject( x, y, 0.0f, mViewMatrix, 0, mProjectionMatrix, 0, viewport, 0, pos1, 0); GLU.gluUnProject( x, y, 1.0f, mViewMatrix, 0, mProjectionMatrix, 0, viewport, 0, pos2, 0); } Just as a reference I've tried transforming the coordinates 0,0,0 and got an offset. It would be appreciated if you would answer using OpenGL ES 2.0 code.

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  • Is there an easy way to read blu-rays on Windows?

    - by ereOn
    Some time ago, I bought my parents a computer dedicated to medias (mostly photographs and movies trough DLNA). My father asked me if he could read blu-ray on it, so I bought a blu-ray reader but I can't find a software to do the playback. I installed PowerDVD (a free version we got with a Blu-Ray) but it seems it now requires a (non-free) upgrade. Even if it were free, I hardly see my parent do the upgrade by themselves as they barely understand how computers work. I thought I would find a free software (something like VLC, but for blu-rays) but so far had no luck. Do you guys have a software to suggest that would solve my issues ? It should run on Windows Vista, shouldn't require an update every monday, or at least a free one. Thank you very much.

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  • how to make shadows for transparent objects using ray tracing in C++/openGL

    - by happy face
    I'm trying to make a code that cast shadow from trasnparent objects(such as glass) for rendering in 3D I do not have a shadow map and photon mapping yet, and I wanted to know if there is a way to make shadows for transparent materials using ray tracing only. Caustics sounds very hard without photon mapping... I have implemented a simple code in C++ that only makes the shadows black (no matter if the objects are transparent or opaque) Pseudo code would be great, thnx. for(size_t i = 0;i < num; ++i) { if(state_list[i].hit && state_list[i].distance < dist_from_light[i]) { return[i] = BLACK; }

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  • Ray Generation Inconsistency

    - by Myx
    I have written code that generates a ray from the "eye" of the camera to the viewing plane some distance away from the camera's eye: R3Ray ConstructRayThroughPixel(...) { R3Point p; double increments_x = (lr.X() - ul.X())/(double)width; double increments_y = (ul.Y() - lr.Y())/(double)height; p.SetX( ul.X() + ((double)i_pos+0.5)*increments_x ); p.SetY( lr.Y() + ((double)j_pos+0.5)*increments_y ); p.SetZ( lr.Z() ); R3Vector v = p-camera_pos; R3Ray new_ray(camera_pos,v); return new_ray; } ul is the upper left corner of the viewing plane and lr is the lower left corner of the viewing plane. They are defined as follows: R3Point org = scene->camera.eye + scene->camera.towards * radius; R3Vector dx = scene->camera.right * radius * tan(scene->camera.xfov); R3Vector dy = scene->camera.up * radius * tan(scene->camera.yfov); R3Point lr = org + dx - dy; R3Point ul = org - dx + dy; Here, org is the center of the viewing plane with radius being the distance between the viewing plane and the camera eye, dx and dy are the displacements in the x and y directions from the center of the viewing plane. The ConstructRayThroughPixel(...) function works perfectly for a camera whose eye is at (0,0,0). However, when the camera is at some different position, not all needed rays are produced for the image. Any suggestions what could be going wrong? Maybe something wrong with my equations? Thanks for the help.

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  • Healthcare and Distributed Data Don't Mix

    - by [email protected]
    How many times have you heard the story?  Hard disk goes missing, USB thumb drive goes missing, laptop goes missing...Not a week goes by that we don't hear about our data going missing...  Healthcare data is a big one, but we hear about credit card data, pricing info, corporate intellectual property...  When I have spoken at Security and IT conferences part of my message is "Why do you give your users data to lose in the first place?"  I don't suggest they can't have access to it...in fact I work for the company that provides the premiere data security and desktop solutions that DO provide access.  Access isn't the issue.  'Keeping the data' is the issue.We are all human - we all make mistakes... I fault no one for having their car stolen or that they dropped a USB thumb drive. (well, except the thieves - I can certainly find some fault there)  Where I find fault is in policy (or lack thereof sometimes) that allows users to carry around private, and important, data with them.  Mr. Director of IT - It is your fault, not theirs.  Ms. CSO - Look in the mirror.It isn't like one can't find a network to access the data from.  You are on a network right now.  How many Wireless ones (wifi, mifi, cellular...) are there around you, right now?  Allowing employees to remove data from the confines of (wait for it... ) THE DATA CENTER is just plain indefensible when it isn't required.  The argument that the laptop had a password and the hard disk was encrypted is ridiculous.  An encrypted drive tells thieves that before they sell the stolen unit for $75, they should crack the encryption and ascertain what the REAL value of the laptop is... credit card info, Identity info, pricing lists, banking transactions... a veritable treasure trove of info people give away on an 'encrypted disk'.What started this latest rant on lack of data control was an article in Government Health IT that was forwarded to me by Denny Olson, an Oracle Principal Sales Consultant in Minnesota.  The full article is here, but the point was that a couple laptops went missing in a couple different cases, and.. well... no one knows where the data is, and yes - they were loaded with patient info.  What were you thinking?Obviously you can't steal data form a Sun Ray appliance... since it has no data, nor any storage to keep the data on, and Secure Global Desktop allows access from Macs, Linux and Windows client devices...  but in all cases, there is no keeping the data unless you explicitly allow for it in your policy.   Since you can get at the data securely from any network, why would you want to take personal responsibility for it?  Both Sun Rays and Secure Global Desktop are widely used in Healthcare... but clearly not widely enough.We need to do a better job of getting the message out -  Healthcare (or insert your business type here) and distributed data don't mix. Then add Hot Desking and 'follow me printing' and you have something that Clinicians (and CSOs) love.Thanks for putting up my blood pressure, Denny.

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  • Better approach to archiving large amounts of original video footage using optical media (DVD/Blu-ra

    - by Rob
    This question is to share my experience as well as ask for suggestions for better methods. Along with 2 friends, I completed the making of a short documentary film in 2006. Clip is at: http://www.youtube.com/mediamotioninvision The film was edited in Adobe Premiere Pro 1.5 on Windows XP. More details and screenshot here: http://www.flickr.com/photos/smilingrobbie/1350235514/ ( note this is not intended to be a plug, we've moved on from this initial learning curve project ;) ) The film is in 4:3 standard definition 720x576 PAL format. As well as retaining the final 30minute film, I wanted to keep all original files that assembled together to make the film. The footage was 83.5Gb So I archived them to over 20 4.7Gb DVD recordables in the original .avi format (i.e. data DVD-ROM format, NOT DVD-Video Mpeg2) Some .avi DV video files were larger than 4.7Gb so I used 7-zip to split them ( here is a guide as to how to do that: http://www.linglom.com/2008/10/12/how-to-split-a-large-file-using-7-zip/ ) To recombine them, a dos shell command like this would do that: copy /b file.avi.* file.avi would do the job, where .* is a wild card to include all the split parts e.g. 001, 002...00n assuming they are all in the same directory path folder. file.avi is the recombined file identical to the original. Later on, I bought a LG BE06 LU10 USB 2.0 Super-multi Blu-ray burner and archived the footage to 2 (two) x 50Gb BD-R DL discs. Again in the original format, written as files to a BD-R in the BD-R BD-ROM UDF format readable by PC/Mac etc, NOT Blu-ray video/film format. This seems to be a good solution for me, because: the archive is in a robust, reasonably permanent, non-volatile medium, i.e. DVD recordable / Blu-ray (debates about stability of optical media organic chemical dye compounds/substrates aside) the format of the archive is accessible by open source tools or just plain Windows Explorer and it's not in a proprietary format I just thought I'd ask folks for their experience on better methods, if such exist.

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  • windvd aacs keys update dosn't work

    - by Jeremy French
    A relative has a viao htpc, which has blue ray. The player I believe is a viao branded version of windvd with blue ray support. Every time it loads it asks if it should update the aacs keys as they are out of date. If you select yes nothing happens. The package just sits there forever saying that you shouldn't turn it off. I have tried to go to the products website (which is now corel) registering and downloading the keys, but the key download page does nothing. Has anyone had a similar problem, or are there any suggestions to get around it?

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  • How do I implement AABB ray cast hit checking for opengl es on the iPhone

    - by Big Fizzy
    Basically, I draw a 3D cube, I can spin it around but I want to be able to touch it and know where on my cube's surface the user touched. I'm using for setting up, generating and spinning. Its based on the Molecules code and NeHe tutorial #5. Any help, links, tutorials and code would be greatly appreciated. I have lots of development experience but nothing much in the way of openGL and 3d. // // GLViewController.h // NeHe Lesson 05 // // Created by Jeff LaMarche on 12/12/08. // Copyright Jeff LaMarche Consulting 2008. All rights reserved. // #import "GLViewController.h" #import "GLView.h" @implementation GLViewController - (void)drawBox { static const GLfloat cubeVertices[] = { -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,-1.0f, 1.0f, -1.0f,-1.0f, 1.0f, -1.0f, 1.0f,-1.0f, 1.0f, 1.0f,-1.0f, 1.0f,-1.0f,-1.0f, -1.0f,-1.0f,-1.0f }; static const GLubyte cubeNumberOfIndices = 36; const GLubyte cubeVertexFaces[] = { 0, 1, 5, // Half of top face 0, 5, 4, // Other half of top face 4, 6, 5, // Half of front face 4, 6, 7, // Other half of front face 0, 1, 2, // Half of back face 0, 3, 2, // Other half of back face 1, 2, 5, // Half of right face 2, 5, 6, // Other half of right face 0, 3, 4, // Half of left face 7, 4, 3, // Other half of left face 3, 6, 2, // Half of bottom face 6, 7, 3, // Other half of bottom face }; const GLubyte cubeFaceColors[] = { 0, 255, 0, 255, 255, 125, 0, 255, 255, 0, 0, 255, 255, 255, 0, 255, 0, 0, 255, 255, 255, 0, 255, 255 }; glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, 0, cubeVertices); int colorIndex = 0; for(int i = 0; i < cubeNumberOfIndices; i += 3) { glColor4ub(cubeFaceColors[colorIndex], cubeFaceColors[colorIndex+1], cubeFaceColors[colorIndex+2], cubeFaceColors[colorIndex+3]); int face = (i / 3.0); if (face%2 != 0.0) colorIndex+=4; glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, &cubeVertexFaces[i]); } glDisableClientState(GL_VERTEX_ARRAY); } //move this to a data model later! - (GLfixed)floatToFixed:(GLfloat)aValue; { return (GLfixed) (aValue * 65536.0f); } - (void)drawViewByRotatingAroundX:(float)xRotation rotatingAroundY:(float)yRotation scaling:(float)scaleFactor translationInX:(float)xTranslation translationInY:(float)yTranslation view:(GLView*)view; { glMatrixMode(GL_MODELVIEW); GLfixed currentModelViewMatrix[16] = { 45146, 47441, 2485, 0, -25149, 26775,-54274, 0, -40303, 36435, 36650, 0, 0, 0, 0, 65536 }; /* GLfixed currentModelViewMatrix[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 65536 }; */ //glLoadIdentity(); //glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -10.0f, 4.0f); // Reset rotation system if (isFirstDrawing) { //glLoadIdentity(); glMultMatrixx(currentModelViewMatrix); [self configureLighting]; isFirstDrawing = NO; } // Scale the view to fit current multitouch scaling GLfixed fixedPointScaleFactor = [self floatToFixed:scaleFactor]; glScalex(fixedPointScaleFactor, fixedPointScaleFactor, fixedPointScaleFactor); // Perform incremental rotation based on current angles in X and Y glGetFixedv(GL_MODELVIEW_MATRIX, currentModelViewMatrix); GLfloat totalRotation = sqrt(xRotation*xRotation + yRotation*yRotation); glRotatex([self floatToFixed:totalRotation], (GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[1] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[0]), (GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[5] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[4]), (GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[9] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[8]) ); // Translate the model by the accumulated amount glGetFixedv(GL_MODELVIEW_MATRIX, currentModelViewMatrix); float currentScaleFactor = sqrt(pow((GLfloat)currentModelViewMatrix[0] / 65536.0f, 2.0f) + pow((GLfloat)currentModelViewMatrix[1] / 65536.0f, 2.0f) + pow((GLfloat)currentModelViewMatrix[2] / 65536.0f, 2.0f)); xTranslation = xTranslation / (currentScaleFactor * currentScaleFactor); yTranslation = yTranslation / (currentScaleFactor * currentScaleFactor); // Grab the current model matrix, and use the (0,4,8) components to figure the eye's X axis in the model coordinate system, translate along that glTranslatef(xTranslation * (GLfloat)currentModelViewMatrix[0] / 65536.0f, xTranslation * (GLfloat)currentModelViewMatrix[4] / 65536.0f, xTranslation * (GLfloat)currentModelViewMatrix[8] / 65536.0f); // Grab the current model matrix, and use the (1,5,9) components to figure the eye's Y axis in the model coordinate system, translate along that glTranslatef(yTranslation * (GLfloat)currentModelViewMatrix[1] / 65536.0f, yTranslation * (GLfloat)currentModelViewMatrix[5] / 65536.0f, yTranslation * (GLfloat)currentModelViewMatrix[9] / 65536.0f); // Black background, with depth buffer enabled glClearColor(0.0f, 0.0f, 0.0f, 1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); [self drawBox]; } - (void)configureLighting; { const GLfixed lightAmbient[] = {13107, 13107, 13107, 65535}; const GLfixed lightDiffuse[] = {65535, 65535, 65535, 65535}; const GLfixed matAmbient[] = {65535, 65535, 65535, 65535}; const GLfixed matDiffuse[] = {65535, 65535, 65535, 65535}; const GLfixed lightPosition[] = {30535, -30535, 0, 0}; const GLfixed lightShininess = 20; glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_COLOR_MATERIAL); glMaterialxv(GL_FRONT_AND_BACK, GL_AMBIENT, matAmbient); glMaterialxv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiffuse); glMaterialx(GL_FRONT_AND_BACK, GL_SHININESS, lightShininess); glLightxv(GL_LIGHT0, GL_AMBIENT, lightAmbient); glLightxv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse); glLightxv(GL_LIGHT0, GL_POSITION, lightPosition); glEnable(GL_DEPTH_TEST); glShadeModel(GL_SMOOTH); glEnable(GL_NORMALIZE); } -(void)setupView:(GLView*)view { const GLfloat zNear = 0.1, zFar = 1000.0, fieldOfView = 60.0; GLfloat size; glMatrixMode(GL_PROJECTION); glEnable(GL_DEPTH_TEST); size = zNear * tanf(DEGREES_TO_RADIANS(fieldOfView) / 2.0); CGRect rect = view.bounds; glFrustumf(-size, size, -size / (rect.size.width / rect.size.height), size / (rect.size.width / rect.size.height), zNear, zFar); glViewport(0, 0, rect.size.width, rect.size.height); glScissor(0, 0, rect.size.width, rect.size.height); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glClearColor(0.0f, 0.0f, 0.0f, 1.0f); glTranslatef(0.0f, 0.0f, -6.0f); isFirstDrawing = YES; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; } - (void)dealloc { [super dealloc]; } @end

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  • Raycasting "fisheye effect" question

    - by mattboy
    Continuing my exploration of raycasting, I am very confused about how the correction of the fisheye effect works. Looking at the screenshot below from the tutorial at permadi.com, the way I understand the cause of the fisheye effect is that the rays that are cast are distances from the player, rather than the distances perpendicular to the screen (or camera plane) which is what really needs to be displayed. The distance perpendicular to the screen then, in my world, should simply be the distance of Y coordinates (Py - Dy) assuming that the player is facing straight upwards. Continuing the tutorial, this is exactly how it seems to be according to the below screenshot. From my point of view, the "distorted distance" below is the same as the distance PD calculated above, and what's labelled the "correct distance" below should be the same as Py - Dy. Yet, this clearly isn't the case according to the tutorial. My question is, WHY is this not the same? How could it not be? What am I understanding and visualizing wrong here?

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  • Oracle Desktop Virtualization Press Release

    - by [email protected]
    Even though Oracle has introduced new products (HW and SW) and pricing, and part numbers, modified licensing, and an EVP and an SVP have discussed openly where Oracle is going with Virtualization,  you may still have heard from "the other guys' that Oracle isn't going to be keeping the legacy Sun 'Desktop' portfolio.  I think that has soundly been addressed by the press release this morning.  Click here for the release.This is a great way to kick off Oracle's New (fiscal) Year.  As there are more announcements coming - I'll just say "Enjoy!, and "Stay Tuned".

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  • An Interview with Wim Coekaerts

    - by [email protected]
    It isn't everyday you get to hear an interview with an SVP at Oracle, nor do you often get glimpses into the future of Oracle products. However - in this interview you get both. listen to Wim talk about Sun Rays, VDI and what Virtual Iron might mean to the mix of products coming...Enjoy

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  • Why doesn't Unity's OnCollisionEnter give me surface normals, and what's the most reliable way to get them?

    - by michael.bartnett
    Unity's on collision event gives you a Collision object that gives you some information about the collision that happened (including a list of ContactPoints with hit normals). But what you don't get is surface normals for the collider that you hit. Here's a screenshot to illustrate. The red line is from ContactPoint.normal and the blue line is from RaycastHit.normal. Is this an instance of Unity hiding information to provide a simplified API? Or do standard 3D realtime collision detection techniques just not collect this information? And for the second part of the question, what's a surefire and relatively efficient way to get a surface normal for a collision? I know that raycasting gives you surface normals, but it seems I need to do several raycasts to accomplish this for all scenarios (maybe a contact point/normal combination misses the collider on the first cast, or maybe you need to do some average of all the contact points' normals to get the best result). My current method: Back up the Collision.contacts[0].point along its hit normal Raycast down the negated hit normal for float.MaxValue, on Collision.collider If that fails, repeat steps 1 and 2 with the non-negated normal If that fails, try steps 1 to 3 with Collision.contacts[1] Repeat 4 until successful or until all contact points exhausted. Give up, return Vector3.zero. This seems to catch everything, but all those raycasts make me queasy, and I'm not sure how to test that this works for enough cases. Is there a better way?

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  • Narrow-phase collision detection algorithms

    - by Marian Ivanov
    There are three phases of collision detection. Broadphase: It loops between all objecs that can interact, false positives are allowed, if it would speed up the loop. Narrowphase: Determines whether they collide, and sometimes, how, no false positives Resolution: Resolves the collision. The question I'm asking is about the narrowphase. There are multiple algorithms, differing in complexity and accuracy. Hitbox intersection: This is an a-posteriori algorithm, that has the lowest complexity, but also isn't too accurate, Color intersection: Hitbox intersection for each pixel, a-posteriori, pixel-perfect, not accuratee in regards to time, higher complexity Separating axis theorem: This is used more often, accurate for triangles, however, a-posteriori, as it can't find the edge, when taking last frame in account, it's more stable Linear raycasting: A-priori algorithm, useful for semi-realistic-looking physics, finds the intersection point, even more accurate than SAT, but with more complexity Spline interpolation: A-priori, even more accurate than linear rays, even more coplexity. There are probably many more that I've forgot about. The question is, in when is it better to use SAT, when rays, when splines, and whether there is anything better.

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  • Optimized algorithm for line-sphere intersection in GLSL

    - by fernacolo
    Well, hello then! I need to find intersection between line and sphere in GLSL. Right now my solution is based on Paul Bourke's page and was ported to GLSL this way: // The line passes through p1 and p2: vec3 p1 = (...); vec3 p2 = (...); // Sphere center is p3, radius is r: vec3 p3 = (...); float r = ...; float x1 = p1.x; float y1 = p1.y; float z1 = p1.z; float x2 = p2.x; float y2 = p2.y; float z2 = p2.z; float x3 = p3.x; float y3 = p3.y; float z3 = p3.z; float dx = x2 - x1; float dy = y2 - y1; float dz = z2 - z1; float a = dx*dx + dy*dy + dz*dz; float b = 2.0 * (dx * (x1 - x3) + dy * (y1 - y3) + dz * (z1 - z3)); float c = x3*x3 + y3*y3 + z3*z3 + x1*x1 + y1*y1 + z1*z1 - 2.0 * (x3*x1 + y3*y1 + z3*z1) - r*r; float test = b*b - 4.0*a*c; if (test >= 0.0) { // Hit (according to Treebeard, "a fine hit"). float u = (-b - sqrt(test)) / (2.0 * a); vec3 hitp = p1 + u * (p2 - p1); // Now use hitp. } It works perfectly! But it seems slow... I'm new at GLSL. You can answer this questions in two ways: Tell me there is no solution, showing some proof or strong evidence. Tell me about GLSL features (vector APIs, primitive operations) that makes the above algorithm faster, showing some example. Thanks a lot!

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  • Finding which tiles are intersected by a line, without looping through all of them or skipping any

    - by JustSuds
    I've been staring at this problem for a few days now. I rigged up this graphic to help me visualise the issue: http://i.stack.imgur.com/HxyP9.png (from the graph, we know that the line intersects [1, 1], [1, 2], [2, 2], [2, 3], ending in [3,3]) I want to step along the line to each grid space and check to see if the material of the grid space is solid. I feel like I already know the math involved, but I haven't been able to string it together yet. I'm using this to test line of sight and eliminate nodes after a path is found via my pathfinding algorithms - my agents cant see through a solid block, therefore they cant move through one, therefore the node is not eliminated from the path because it is required to navigate a corner. So, I need an algorithm that will step along the line to each grid space that it intersects. Any ideas? I've taken a look at a lot of common algorithms, like Bresenham's, and one that steps at predefined intervals along the line (unfortunately, this method skips tiles if they're intersecting with a smaller wedge than the step size). I'm populating my whiteboard now with a mass of floor() and ceil() functions - but its getting overly complicated and I'm afraid it might cause a slowdown.

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  • 202 blog articles

    - by mprove
    All my blog articles under blogs.oracle.com since August 2005: 202 blog articles Apr 2012 blogs.oracle.com design patch Mar 2012 Interaction 12 - Critique Mar 2012 Typing. Clicking. Dancing. Feb 2012 Desktop Mobility in Hospitals with Oracle VDI /video Feb 2012 Interaction 12 in Dublin - Highlights of Day 3 Feb 2012 Interaction 12 in Dublin - Highlights of Day 2 Feb 2012 Interaction 12 in Dublin - Highlights of Day 1 Feb 2012 Shit Interaction Designers Say Feb 2012 Tips'n'Tricks for WebCenter #3: How to display custom page titles in Spaces Jan 2012 Tips'n'Tricks for WebCenter #2: How to create an Admin menu in Spaces and save a lot of time Jan 2012 Tips'n'Tricks for WebCenter #1: How to apply custom resources in Spaces Jan 2012 Merry XMas and a Happy 2012! Dec 2011 One Year Oracle SocialChat - The Movie Nov 2011 Frank Ludolph's Last Working Day Nov 2011 Hans Rosling at TED Oct 2011 200 Countries x 200 Years Oct 2011 Blog Aggregation for Desktop Virtualization Oct 2011 Oracle VDI at OOW 2011 Sep 2011 Design for Conversations & Conversations for Design Sep 2011 All Oracle UX Blogs Aug 2011 Farewell Loriot Aug 2011 Oracle VDI 3.3 Overview Aug 2011 Sutherland's Closing Remarks at HyperKult Aug 2011 Surface and Subface Aug 2011 Back to Childhood in UI Design Jul 2011 The Art of Engineering and The Engineering of Art Jul 2011 Oracle VDI Seminar - June-30 Jun 2011 SGD White Paper May 2011 TEDxHamburg Live Feed May 2011 Oracle VDI in 3 Minutes May 2011 Space Ship Earth 2011 May 2011 blog moving times Apr 2011 Frozen tag cloud Apr 2011 Oracle: Hardware Software Complete in 1953 Apr 2011 Interaction Design with Wireframes Apr 2011 A guide to closing down a project Feb 2011 Oracle VDI 3.2.2 Jan 2011 free VDI charts Jan 2011 Sun Founders Panel 2006 Dec 2010 Sutherland on Leadership Dec 2010 SocialChat: Efficiency of E20 Dec 2010 ALWAYS ON Desktop Virtualization Nov 2010 12,000 Desktops at JavaOne Nov 2010 SocialChat on Sharing Best Practices Oct 2010 Globe of Visitors Oct 2010 SocialChat about the Next Big Thing Oct 2010 Oracle VDI UX Story - Wireframes Oct 2010 What's a PC anyway? Oct 2010 SocialChat on Getting Things Done Oct 2010 SocialChat on Infoglut Oct 2010 IT Twenty Twenty Oct 2010 Desktop Virtualization Webcasts from OOW Oct 2010 Oracle VDI 3.2 Overview Sep 2010 Blog Usability Top 7 Sep 2010 100 and counting Aug 2010 Oracle'izing the VDI Blogs Aug 2010 SocialChat on Apple Aug 2010 SocialChat on Video Conferencing Aug 2010 Oracle VDI 3.2 - Features and Screenshots Aug 2010 SocialChat: Don't stop making waves Aug 2010 SocialChat: Giving Back to the Community Aug 2010 SocialChat on Learning in Meetings Aug 2010 iPAD's Natural User Interface Jul 2010 Last day for Sun Microsystems GmbH Jun 2010 SirValUse Celebration Snippets Jun 2010 10 years SirValUse - Happy Birthday! Jun 2010 Wim on Virtualization May 2010 New Home for Oracle VDI Apr 2010 Renaissance Slide Sorter Comments Apr 2010 Unboxing Sun Ray 3 Plus Apr 2010 Desktop Virtualisierung mit Sun VDI 3.1 Apr 2010 Blog Relaunch Mar 2010 Social Messaging Slides from CeBIT Mar 2010 Social Messaging Talk at CeBIT Feb 2010 Welcome Oracle Jan 2010 My last presentation at Sun Jan 2010 Ivan Sutherland on Leadership Jan 2010 Learning French with Sun VDI Jan 2010 Learning Danish with Sun Ray Jan 2010 VDI workshop in Nieuwegein Jan 2010 Happy New Year 2010 Jan 2010 On Creating Slides Dec 2009 Best VDI Ever Nov 2009 How to store the Big Bang Nov 2009 Social Enterprise Tools. Beipiel Sun. Nov 2009 Nov-19 Nov 2009 PDF and ODF links on your blog Nov 2009 Q&A on VDI and MySQL Cluster Nov 2009 Zürich next week: Swiss Intranet Summit 09 Nov 2009 Designing for a Sustainable World - World Usabiltiy Day, Nov-12 Nov 2009 How to export a desktop from VDI 3 Nov 2009 Virtualisation Roadshow in the UK Nov 2009 Project Wonderland at EDUCAUSE 09 Nov 2009 VDI Roadshow in Dublin, Nov-26, 2009 Nov 2009 Sun VDI at EDUCAUSE 09 Nov 2009 Sun VDI 3.1 Architecture and New Features Oct 2009 VDI 3.1 is Early-Access Sep 2009 Virtualization for MySQL on VMware Sep 2009 Silpion & 13. Stock Sommerparty Sep 2009 Sun Ray and VMware View 3.1.1 2009-08-31 New Set of Sun Ray Status Icons 2009-08-25 Virtualizing the VDI Core? 2009-08-23 World Usability Day Hamburg 2009 - CfP 2009-07-16 Rising Sun 2009-07-15 featuring twittermeme 2009-06-19 ISC09 Student Party on June-20 /Hamburg 2009-06-18 Before and behind the curtain of JavaOne 2009-06-09 20k desktops at JavaOne 2009-06-01 sweet microblogging 2009-05-25 VDI 3 - Why you need 3 VDI hosts and what you can do about that? 2009-05-21 IA Konferenz 2009 2009-05-20 Sun VDI 3 UX Story - Power of the Web 2009-05-06 Planet of Sun and Oracle User Experience Design 2009-04-22 Sun VDI 3 UX Story - User Research 2009-04-08 Sun VDI 3 UX Story - Concept Workshops 2009-04-06 Localized documentation for Sun Ray Connector for VMware View Manager 1.1 2009-04-03 Sun VDI 3 Press Release 2009-03-25 Sun VDI 3 launches today! 2009-03-25 Sun Ray Connector for VMware View Manager 1.1 Update 2009-03-11 desktop virtualization wiki relaunch 2009-03-06 VDI 3 at CeBIT hall 6, booth E36 2009-03-02 Keyboard layout problems with Sun Ray Connector for VMware VDM 2009-02-23 wikis.sun.com tips & tricks 2009-02-23 Sun VDI 3 is in Early Access 2009-02-09 VirtualCenter unable to decrypt passwords 2009-02-02 Sun & VMware Desktop Training 2009-01-30 VDI at next09? 2009-01-16 Sun VDI: How to use virtual machines with multiple network adapters 2009-01-07 Sun Ray and VMware View 2009-01-07 Hamburg World Usability Day 2008 - Webcasts 2009-01-06 Sun Ray Connector for VMware VDM slides 2008-12-15 mother of all demos 2008-12-08 Build your own Thumper 2008-12-03 Troubleshooting Sun Ray Connector for VMware VDM 2008-12-02 My Roller Tag Cloud 2008-11-28 Sun Ray Connector: SSL connection to VDM 2008-11-25 Setting up SSL and Sun Ray Connector for VMware VDM 2008-11-13 Inspiration for Today and Tomorrow 2008-10-23 Sun Ray Connector for VMware VDM released 2008-10-14 From Sketchpad to ILoveSketch 2008-10-09 Desktop Virtualization on Xing 2008-10-06 User Experience Forum on Xing 2008-10-06 Sun Ray Connector for VMware VDM certified 2008-09-17 Virtual Clouds over Las Vegas 2008-09-14 Bill Verplank sketches metaphors 2008-09-04 End of Early Access - Sun Ray Connector for VMware 2008-08-27 Early Access: Sun Ray Connector for VMware Virtual Desktop Manager 2008-08-12 Sun Virtual Desktop Connector - Insides on Recycling Part 2 2008-07-20 Sun Virtual Desktop Connector - Insides on Recycling Part 3 2008-07-20 Sun Virtual Desktop Connector - Insides on Recycling 2008-07-20 lost in wiki space 2008-07-07 Evolution of the Desktop 2008-06-17 Virtual Desktop Webcast 2008-06-16 Woodstock 2008-06-16 What's a Desktop PC anyway? 2008-06-09 Virtual-T-Box 2008-06-05 Virtualization Glossary 2008-05-06 Five User Experience Principles 2008-04-25 Virtualization News Feed 2008-04-21 Acetylcholinesterase - Second Season 2008-04-18 Acetylcholinesterase - End of Signal 2007-12-31 Produkt-Management ist... 2007-10-22 Usability Verbände, Verteiler und Netzwerke. 2007-10-02 The Meaning is the Message 2007-09-28 Visualization Methods 2007-09-10 Inhouse und Open Source Projekte – Usability verankern und Synergien nutzen 2007-09-03 Der Schwabe Darth Vader entdeckt das Virale Marketing 2007-08-29 Dick Hardt 3.0 on Identity 2.0 2007-08-27 quality of written text depends on the tool 2007-07-27 podcasts for reboot9 2007-06-04 It is the user's itch that need to be scratched 2007-05-25 A duel at reboot9 2007-05-14 Taxonomien und Folksonomien - Tagging als neues HCI-Element 2007-05-10 Dueling Interaction Models of Personal-Computing and Web-Computing 2007-03-01 22.März: Weizenbaum. Rebel at Work. /Filmpremiere Hamburg 2007-02-25 Bruce Sterling at UbiComp 2006 /webcast 2006-11-12 FSOSS 2006 /webcasts 2006-11-10 Highway 101 2006-11-09 User Experience Roundtable Hamburg: EuroGEL 2006 2006-11-08 Douglas Adams' Hyperland (BBC 1990) 2006-10-08 Taxonomien und Folksonomien – Tagging als neues HCI-Element 2006-09-13 Usability im Unternehmen 2006-09-13 Doug does HyperScope 2006-08-26 TED Talks and TechTalks 2006-08-21 Kai Krause über seine Freundschaft zu Douglas Adams 2006-07-20 Rebel At Work: Film Portrait on Weizenbaum 2006-07-04 Gabriele Fischer, mp3 2006-06-07 Dick Hardt at ETech 06 2006-06-05 Weinberger: From Control to Conversation 2006-04-16 Eye Tracking at User Experience Roundtable Hamburg 2006-04-14 dropping knowledge 2006-04-09 GEL 2005 2006-03-13 slide photos of reboot7 2006-03-04 Dick Hardt on Identity 2.0 2006-02-28 User Experience Newsletter #13: Versioning 2006-02-03 Ester Dyson on Choice and Happyness 2006-02-02 Requirements-Engineering im Spannungsfeld von Individual- und Produktsoftware 2006-01-15 User Experience Newsletter #12: Intuition Quiz 2005-11-30 User Experience und Requirements-Engineering für Software-Projekte 2005-10-31 Ivan Sutherland on "Research and Fun" 2005-10-18 Ars Electronica / Mensch und Computer 2005 2005-09-14 60 Jahre nach Memex: Über die Unvereinbarkeit von Desktop- und Web-Paradigma 2005-08-31 reboot 7 2005-06-30

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  • My raycaster is putting out strange results, how do I fix it?

    - by JamesK89
    I'm working on a raycaster in ActionScript 3.0 for the fun of it, and as a learning experience. I've got it up and running and its displaying me output as expected however I'm getting this strange bug where rays go through corners of blocks and the edges of blocks appear through walls. Maybe somebody with more experience can point out what I'm doing wrong or maybe a fresh pair of eyes can spot a tiny bug I haven't noticed. Thank you so much for your help! Screenshots: http://i55.tinypic.com/25koebm.jpg http://i51.tinypic.com/zx5jq9.jpg Relevant code: function drawScene() { rays.graphics.clear(); rays.graphics.lineStyle(1, rgba(0x00,0x66,0x00)); var halfFov = (player.fov/2); var numRays:int = ( stage.stageWidth / COLUMN_SIZE ); var prjDist = ( stage.stageWidth / 2 ) / Math.tan(toRad( halfFov )); var angStep = ( player.fov / numRays ); for( var i:int = 0; i < numRays; i++ ) { var rAng = ( ( player.angle - halfFov ) + ( angStep * i ) ) % 360; if( rAng < 0 ) rAng += 360; var ray:Object = castRay(player.position, rAng); drawRaySlice(i*COLUMN_SIZE, prjDist, player.angle, ray); } } function drawRaySlice(sx:int, prjDist, angle, ray:Object) { if( ray.distance >= MAX_DIST ) return; var height:int = int(( TILE_SIZE / (ray.distance * Math.cos(toRad(angle-ray.angle))) ) * prjDist); if( !height ) return; var yTop = int(( stage.stageHeight / 2 ) - ( height / 2 )); if( yTop < 0 ) yTop = 0; var yBot = int(( stage.stageHeight / 2 ) + ( height / 2 )); if( yBot > stage.stageHeight ) yBot = stage.stageHeight; rays.graphics.moveTo( (ray.origin.x / TILE_SIZE) * MINI_SIZE, (ray.origin.y / TILE_SIZE) * MINI_SIZE ); rays.graphics.lineTo( (ray.hit.x / TILE_SIZE) * MINI_SIZE, (ray.hit.y / TILE_SIZE) * MINI_SIZE ); for( var x:int = 0; x < COLUMN_SIZE; x++ ) { for( var y:int = yTop; y < yBot; y++ ) { buffer.setPixel(sx+x, y, clrTable[ray.tile-1] >> ( ray.horz ? 1 : 0 )); } } } function castRay(origin:Point, angle):Object { // Return values var rTexel = 0; var rHorz = false; var rTile = 0; var rDist = MAX_DIST + 1; var rMap:Point = new Point(); var rHit:Point = new Point(); // Ray angle and slope var ra = toRad(angle) % ANGLE_360; if( ra < ANGLE_0 ) ra += ANGLE_360; var rs = Math.tan(ra); var rUp = ( ra > ANGLE_0 && ra < ANGLE_180 ); var rRight = ( ra < ANGLE_90 || ra > ANGLE_270 ); // Ray position var rx = 0; var ry = 0; // Ray step values var xa = 0; var ya = 0; // Ray position, in map coordinates var mx:int = 0; var my:int = 0; var mt:int = 0; // Distance var dx = 0; var dy = 0; var ds = MAX_DIST + 1; // Horizontal intersection if( ra != ANGLE_180 && ra != ANGLE_0 && ra != ANGLE_360 ) { ya = ( rUp ? TILE_SIZE : -TILE_SIZE ); xa = ya / rs; ry = int( origin.y / TILE_SIZE ) * ( TILE_SIZE ) + ( rUp ? TILE_SIZE : -1 ); rx = origin.x + ( ry - origin.y ) / rs; mx = 0; my = 0; while( mx >= 0 && my >= 0 && mx < world.size.x && my < world.size.y ) { mx = int( rx / TILE_SIZE ); my = int( ry / TILE_SIZE ); mt = getMapTile(mx,my); if( mt > 0 && mt < 9 ) { dx = rx - origin.x; dy = ry - origin.y; ds = ( dx * dx ) + ( dy * dy ); if( rDist >= MAX_DIST || ds < rDist ) { rDist = ds; rTile = mt; rMap.x = mx; rMap.y = my; rHit.x = rx; rHit.y = ry; rHorz = true; rTexel = int(rx % TILE_SIZE) } break; } rx += xa; ry += ya; } } // Vertical intersection if( ra != ANGLE_90 && ra != ANGLE_270 ) { xa = ( rRight ? TILE_SIZE : -TILE_SIZE ); ya = xa * rs; rx = int( origin.x / TILE_SIZE ) * ( TILE_SIZE ) + ( rRight ? TILE_SIZE : -1 ); ry = origin.y + ( rx - origin.x ) * rs; mx = 0; my = 0; while( mx >= 0 && my >= 0 && mx < world.size.x && my < world.size.y ) { mx = int( rx / TILE_SIZE ); my = int( ry / TILE_SIZE ); mt = getMapTile(mx,my); if( mt > 0 && mt < 9 ) { dx = rx - origin.x; dy = ry - origin.y; ds = ( dx * dx ) + ( dy * dy ); if( rDist >= MAX_DIST || ds < rDist ) { rDist = ds; rTile = mt; rMap.x = mx; rMap.y = my; rHit.x = rx; rHit.y = ry; rHorz = false; rTexel = int(ry % TILE_SIZE); } break; } rx += xa; ry += ya; } } return { angle: angle, distance: Math.sqrt(rDist), hit: rHit, map: rMap, tile: rTile, horz: rHorz, origin: origin, texel: rTexel }; }

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  • Pointers to Derived Class Objects Losing vfptr

    - by duckworthd
    To begin, I am trying to write a run-of-the-mill, simple Ray Tracer. In my Ray Tracer, I have multiple types of geometries in the world, all derived from a base class called "SceneObject". I've included the header for it here. /** Interface for all objects that will appear in a scene */ class SceneObject { public: mat4 M, M_inv; Color c; SceneObject(); ~SceneObject(); /** The transformation matrix to be applied to all points of this object. Identity leaves the object in world frame. */ void setMatrix(mat4 M); void setMatrix(MatrixStack mStack); void getMatrix(mat4& M); /** The color of the object */ void setColor(Color c); void getColor(Color& c); /** Alter one portion of the color, leaving the rest as they were. */ void setDiffuse(vec3 rgb); void setSpecular(vec3 rgb); void setEmission(vec3 rgb); void setAmbient(vec3 rgb); void setShininess(double s); /** Fills 'inter' with information regarding an intersection between this object and 'ray'. Ray should be in world frame. */ virtual void intersect(Intersection& inter, Ray ray) = 0; /** Returns a copy of this SceneObject */ virtual SceneObject* clone() = 0; /** Print information regarding this SceneObject for debugging */ virtual void print() = 0; }; As you can see, I've included a couple virtual functions to be implemented elsewhere. In this case, I have only two derived class -- Sphere and Triangle, both of which implement the missing member functions. Finally, I have a Parser class, which is full of static methods that do the actual "Ray Tracing" part. Here's a couple snippets for relevant portions void Parser::trace(Camera cam, Scene scene, string outputFile, int maxDepth) { int width = cam.getNumXPixels(); int height = cam.getNumYPixels(); vector<vector<vec3>> colors; colors.clear(); for (int i = 0; i< width; i++) { vector<vec3> ys; for (int j = 0; j<height; j++) { Intersection intrsct; Ray ray; cam.getRay(ray, i, j); vec3 color; printf("Obtaining color for Ray[%d,%d]\n", i,j); getColor(color, scene, ray, maxDepth); ys.push_back(color); } colors.push_back(ys); } printImage(colors, width, height, outputFile); } void Parser::getColor(vec3& color, Scene scene, Ray ray, int numBounces) { Intersection inter; scene.intersect(inter,ray); if(inter.isIntersecting()){ Color c; inter.getColor(c); c.getAmbient(color); } else { color = vec3(0,0,0); } } Right now, I've forgone the true Ray Tracing part and instead simply return the color of the first object hit, if any. As you have no doubt noticed, the only way the computer knows that a ray has intersected an object is through Scene.intersect(), which I also include. void Scene::intersect(Intersection& i, Ray r) { Intersection result; result.setDistance(numeric_limits<double>::infinity()); result.setIsIntersecting(false); double oldDist; result.getDistance(oldDist); /* Cycle through all objects, making result the closest one */ for(int ind=0; ind<objects.size(); ind++){ SceneObject* thisObj = objects[ind]; Intersection betterIntersect; thisObj->intersect(betterIntersect, r); double newDist; betterIntersect.getDistance(newDist); if (newDist < oldDist){ result = betterIntersect; oldDist = newDist; } } i = result; } Alright, now for the problem. I begin by creating a scene and filling it with objects outside of the Parser::trace() method. Now for some odd reason, I cast Ray for i=j=0 and everything works wonderfully. However, by the time the second ray is cast all of the objects stored in my Scene no longer recognize their vfptr's! I stepped through the code with a debugger and found that the information to all the vfptr's are lost somewhere between the end of getColor() and the continuation of the loop. However, if I change the arguments of getColor() to use a Scene& instead of a Scene, then no loss occurs. What crazy voodoo is this?

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  • What is a technique for 2D ray-box intersection that is suitable for old console hardware?

    - by DJCouchyCouch
    I'm working on a Sega Genesis homebrew game (it has a 7mhz 68000 CPU). I'm looking for a way to find the intersection between a particle sprite and a background tile. Particles are represented as a point with a movement vector. Background tiles are 8 x 8 pixels, with an (X,Y) position that is always located at a multiple of 8. So, really, I need to find the intersection point for a ray-box collision; I need to find out where along the edge of the tile the ray/particle hits. I have these two hard constraints: I'm working with pixel locations (integers). Floating point is too expensive. It doesn't have to be super exact, just close enough. Multiplications, divisions, dot products, et cetera, are incredibly expensive and are to be avoided. So I'm looking for an efficient algorithm that would fit those constraints. Any ideas? I'm writing it in C, so that would work, but assembly should be good as well.

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  • Windows 8 will only recognize the Blu Ray ROM, if the install disk is present at boot time

    - by aceinthehole
    If I have the install disk in the blu ray ROM drive at boot time and subsequently remove the disk and replace it with blu ray media everything functions as I'd expect. However, if I have no media present, or another disk in the drive at boot time, then windows 8 does not seem to recognize that the blu ray player is even present in the computer. It is not present in the 'my computer' screen, device manager does not show the player, and scanning for new hardware yields nothing. It seems that the driver is installed and working as expect, what is it about having the windows 8 install disk in the drive or not that would cause this kind of behavior?

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