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  • Why does casting a NaN to a long yeild a valid result?

    - by brainimus
    In the sample code below I am dividing by zero which when I step through it with the debugger the (dividend / divisor) yeilds an Infinity or NaN (if the divisor is zero). When I cast this result to a long I get a valid result, usually something like -9223372036854775808. Why is this cast valid? Why doesn't it stop executing (throw an exception for example) rather than assign an arbitrary value? double divisor = 0; double dividend = 7; long result = (long)(dividend / divisor);

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  • C++ and C#, "Casting" Functions to Delegates, What's the scoop?

    - by Jacob G
    In C# 2.0, I can do the following: public class MyClass { delegate void MyDelegate(int myParam); public MyClass(OtherObject obj) { //THIS IS THE IMPORTANT PART obj.SomeCollection.Add((MyDelegate)MyFunction); } private void MyFunction(int myParam); { //... } } Trying to implement the same thing in C++, it appears I have to do: MyDelegate del = gcnew MyDelegate(this, MyFunction); obj-SomeCollection-Add(del); Obviously I can create a new instance of the delegate in C# as well instead of what's going on up there. Is there some kind of magic going on in the C# world that doesn't exist in C++ that allows that cast to work? Some kind of magic anonymous delegate? Thanks.

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  • Casting as Interface? Awesome.

    - by cam
    I was just experimenting around with one of my programs, trying to make it looks prettier and I found something interesting. I have an interface that 4 classes inherit from. I found that if I pass the Class as an object to a method like so: ClassTest classtest = new ClassTest(); DoOperation(classtest); private void DoOperation(object o) { ((InterfaceClass)o).DoThis(); } So I can pass any type of class that inherits from InterfaceClass, and it will preform the proper interface operation? This is the coolest thing I've ever found from OOP (something I've never really studied) I really thought interfaces were created for the sole purpose of organization for developers. Are there more uses for interfaces than this?

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  • Why does casting a NaN to a long yield a valid result?

    - by brainimus
    In the sample code below I am dividing by zero which when I step through it with the debugger the (dividend / divisor) yields an Infinity or NaN (if the divisor is zero). When I cast this result to a long I get a valid result, usually something like -9223372036854775808. Why is this cast valid? Why doesn't it stop executing (throw an exception for example) rather than assign an arbitrary value? double divisor = 0; double dividend = 7; long result = (long)(dividend / divisor);

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  • Why does casting to double using "String * 1" fail? Will CDbl(String) work on all systems?

    - by Jamie Bull
    I have an application which contains the line below to assign a parsed XML value to a variant array. V(2) = latNode.Text * 1 This works fine on my system (Windows 7, Excel 2010) but doesn't work on some other system or systems - and I've not been able to get a response from the user who reported the problem. I've switched out the offending line for: V(2) = CDbl(latNode.Text) This still works on my system, but then I had no problem in the first place. The question is on what systems does the first approach fail and why, and will the second method always work? I'm sure I've used the "Stying * 1" trick elsewhere before and would like to know how concerned I should be about tracking down other occurrences. Thanks.

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  • C++/CLI and C#, "Casting" Functions to Delegates, What's the scoop?

    - by Jacob G
    In C# 2.0, I can do the following: public class MyClass { delegate void MyDelegate(int myParam); public MyClass(OtherObject obj) { //THIS IS THE IMPORTANT PART obj.SomeCollection.Add((MyDelegate)MyFunction); } private void MyFunction(int myParam); { //... } } Trying to implement the same thing in C++/CLI, it appears I have to do: MyDelegate del = gcnew MyDelegate(this, MyFunction); obj-SomeCollection-Add(del); Obviously I can create a new instance of the delegate in C# as well instead of what's going on up there. Is there some kind of magic going on in the C# world that doesn't exist in C++/CLI that allows that cast to work? Some kind of magic anonymous delegate? Thanks.

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  • Casting/dereferencing member variable pointer from void*, is this safe?

    - by Damien
    Hi all, I had a problem while hacking a bigger project so I made a simpel test case. If I'm not omitting something, my test code works fine, but maybe it works accidentally so I wanted to show it to you and ask if there are any pitfalls in this approach. I have an OutObj which has a member variable (pointer) InObj. InObj has a member function. I send the address of this member variable object (InObj) to a callback function as void*. The type of this object never changes so inside the callback I recast to its original type and call the aFunc member function in it. In this exampel it works as expected, but in the project I'm working on it doesn't. So I might be omitting something or maybe there is a pitfall here and this works accidentally. Any comments? Thanks a lot in advance. (The problem I have in my original code is that InObj.data is garbage). #include <stdio.h> class InObj { public: int data; InObj(int argData); void aFunc() { printf("Inside aFunc! data is: %d\n", data); }; }; InObj::InObj(int argData) { data = argData; } class OutObj { public: InObj* objPtr; OutObj(int data); ~OutObj(); }; OutObj::OutObj(int data) { objPtr = new InObj(data); } OutObj::~OutObj() { delete objPtr; } void callback(void* context) { ((InObj*)context)->aFunc(); } int main () { OutObj a(42); callback((void*)a.objPtr); }

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  • Calling child constructor by casting (ChildClass)parentObject; to track revisions

    - by FreshCode
    To track revisions of a Page class, I have a PageRevision class which inherits from Page and adds a revision ID (Guid RevisionID;). If possible, how should I cast an existing Page object to a PageRevision and ensure that the PageRevision constructor is called to create a new revision ID? I could could have a PageRevision(Page page) constructor which generates the Guid and copies all the Page attributes, but I want to automate it, especially if a Page class has many attributes (and I later add one, and forget to modify the copy constructor). Desired use Page page = new Page(123, "Page Title", "Page Body"); // where 123 is page ID PageRevision revision = (PageRevision)page; // now revision.RevisionID should be a new Guid. Page, PageRevision classes: public class Page { public int ID { get; set; } public string Title { get; set; } public string Body { get; set; } } public class PageRevision : Page { public Guid RevisionID { get; set; } public PageRevision() { this.RevisionID = Guid.NewGuid(); } }

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  • Camera Projection back Into 3D world, offset error

    - by Anthony
    I'm using XNA to simulate a robot in a 3D world and then do image analysis on what the camera sees. I have my camera looking down in front of the direction that the robot is going, and I have the robot detecting white pixels. I'm trying to take the white pixels that it finds and project them back into the 3D world so that I can see if it is actually detecting the correct pixels. I almost have it working, but there is an offset between where the white is in in the World and were I put my orange triangles (which represent what the robot things is white). /// <summary> /// Takes a bool map of and makes vertex positions based on the map. /// </summary> /// <param name="c"> The bool map</param> private void ProjectBoolMapOnGroundAnthony2(bool[,] c) { float triangleSize = 0.04f; // Point of interest in World W cordinate system. Vector3 pointOfInterest_W = Vector3.Zero; // Point of interest in Robot Cordinate system R Vector3 pointOfInterest_R = Vector3.Zero; // alpha is the angle from the robot camera to where it is looking in the center. //double alpha = Math.Atan(1.8f / 1); /// Matrix representation of the view determined by the position, target, and updirection. Matrix View = ((SimulationMain)Game).mainRobot.robotCameraView.View; /// Matrix representation of the view determined by the angle of the field of view (Pi/4), aspectRatio, nearest plane visible (1), and farthest plane visible (1200) Matrix Projection = ((SimulationMain)Game).mainRobot.robotCameraView.Projection; /// Matrix representing how the real world cordinates differ from that of the rendering by the camera. Matrix World = ((SimulationMain)Game).mainRobot.robotCameraView.World; Plane groundPlan = new Plane(Vector3.UnitZ, 0.0f); for (int x = 0; x < this.screenWidth; x++) { for (int y = 0; y < this.screenHeight; ) { if (c[x, y] == true && this.count1D < 62000) { int j = 1; Vector3 nearPlanePoint = Game.GraphicsDevice.Viewport.Unproject(new Vector3(x, y, 0), Projection, View, World); Vector3 farPlanePoint = Game.GraphicsDevice.Viewport.Unproject(new Vector3(x, y, 1), Projection, View, World); //Vector3 pointOfInterest_W = Vector3.in Ray ray = new Ray(nearPlanePoint, farPlanePoint); pointOfInterest_W = ray.Position + ray.Direction * (float) ray.Intersects(groundPlan); this.vertexArray2[this.count1D + 0].Position.X = pointOfInterest_W.X - triangleSize; this.vertexArray2[this.count1D + 0].Position.Y = pointOfInterest_W.Y - triangleSize * j; this.vertexArray2[this.count1D + 0].Position.Z = pointOfInterest_W.Z; this.vertexArray2[this.count1D + 0].Color = Color.DarkOrange; // Put another vertex a the position but +1 in the X direction triangleSize //this.vertexArray2[this.count1D + 1].Position.X = pointOnGroud.X + 3; //this.vertexArray2[this.count1D + 1].Position.Y = pointOnGroud.Y + j; this.vertexArray2[this.count1D + 1].Position.X = pointOfInterest_W.X; this.vertexArray2[this.count1D + 1].Position.Y = pointOfInterest_W.Y + triangleSize * j; this.vertexArray2[this.count1D + 1].Position.Z = pointOfInterest_W.Z; this.vertexArray2[this.count1D + 1].Color = Color.Red; // Put another vertex a the position but +1 in the X direction //this.vertexArray2[this.count1D + 0].Position.X = pointOnGroud.X; //this.vertexArray2[this.count1D + 0].Position.Y = pointOnGroud.Y + 3 + j; this.vertexArray2[this.count1D + 2].Position.X = pointOfInterest_W.X + triangleSize; this.vertexArray2[this.count1D + 2].Position.Y = pointOfInterest_W.Y - triangleSize * j; this.vertexArray2[this.count1D + 2].Position.Z = pointOfInterest_W.Z; this.vertexArray2[this.count1D + 2].Color = Color.Orange; this.count1D += 3; y += j; } else { y++; } } } } The world is a grass texture with lines on it. The world plane is normal at (0,0,1). Any ideas on why there is an offset? Any Ideas? Thanks for the help, Anthony G.

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  • Raycasting mouse coordinates to rotated object?

    - by SPL
    I am trying to cast a ray from my mouse to a plane at a specified position with a known width and length and height. I know that you can use the NDC (Normalized Device Coordinates) to cast ray but I don't know how can I detect if the ray actually hit the plane and when it did. The plane is translated -100 on the Y and rotated 60 on the X then translated again -100. Can anyone please give me a good tutorial on this? For a complete noob! I am almost new to matrix and vector transformations.

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  • Converting openGl code to DirectX

    - by Fredrik Boston Westman
    First of all, this is kind of a follow up question on @byte56 excellent anwser on this question concerning picking algorithms. I'm trying to convert one of his code examples to directX 11 however I have run in to some problems ( I can pick but the picking is way off), and I wanted to make sure I had done it rigth before moving on and checking the rest of my code. I am not that familiar with openGl but I can imagine openGl has diffrent coordinations systems, and functions that alters how you must implement to code abit. This is his code example: public Ray GetPickRay() { int mouseX = Mouse.getX(); int mouseY = WORLD.Byte56Game.getHeight() - Mouse.getY(); float windowWidth = WORLD.Byte56Game.getWidth(); float windowHeight = WORLD.Byte56Game.getHeight(); //get the mouse position in screenSpace coords double screenSpaceX = ((float) mouseX / (windowWidth / 2) - 1.0f) * aspectRatio; double screenSpaceY = (1.0f - (float) mouseY / (windowHeight / 2)); double viewRatio = Math.tan(((float) Math.PI / (180.f/ViewAngle) / 2.00f))* zoomFactor; screenSpaceX = screenSpaceX * viewRatio; screenSpaceY = screenSpaceY * viewRatio; //Find the far and near camera spaces Vector4f cameraSpaceNear = new Vector4f((float) (screenSpaceX * NearPlane), (float) (screenSpaceY * NearPlane), (float) (-NearPlane), 1); Vector4f cameraSpaceFar = new Vector4f((float) (screenSpaceX * FarPlane), (float) (screenSpaceY * FarPlane), (float) (-FarPlane), 1); //Unproject the 2D window into 3D to see where in 3D we're actually clicking Matrix4f tmpView = Matrix4f(view); Matrix4f invView = (Matrix4f) tmpView.invert(); Vector4f worldSpaceNear = new Vector4f(); Matrix4f.transform(invView, cameraSpaceNear, worldSpaceNear); Vector4f worldSpaceFar = new Vector4f(); Matrix4f.transform(invView, cameraSpaceFar, worldSpaceFar); //calculate the ray position and direction Vector3f rayPosition = new Vector3f(worldSpaceNear.x, worldSpaceNear.y, worldSpaceNear.z); Vector3f rayDirection = new Vector3f(worldSpaceFar.x - worldSpaceNear.x, worldSpaceFar.y - worldSpaceNear.y, worldSpaceFar.z - worldSpaceNear.z); rayDirection.normalise(); return new Ray(rayPosition, rayDirection); } All rigths reserved to him of course This is my DirectX 11 code : void GraphicEngine::pickRayVector(float mouseX, float mouseY,XMVECTOR& pickRayInWorldSpacePos, XMVECTOR& pickRayInWorldSpaceDir) { float PRVecX, PRVecY; float nearPlane = 0.1f; float farPlane = 200.0f; floar viewAngle = 0.4 * 3.14; PRVecX = ((( 2.0f * mouseX) / ClientWidth ) - 1 ) * tan((viewAngle)/2); PRVecY = (1-(( 2.0f * mouseY) / ClientHeight)) * tan((viewAngle)/2); XMVECTOR cameraSpaceNear = XMVectorSet(PRVecX * nearPlane,PRVecY * nearPlane, -nearPlane, 1.0f); XMVECTOR cameraSpaceFar = XMVectorSet(PRVecX * farPlane,PRVecY * farPlane, -farPlane, 1.0f); // Transform 3D Ray from View space to 3D ray in World space XMMATRIX invMat; XMVECTOR matInvDeter; invMat = XMMatrixInverse(&matInvDeter, cam->getCameraView()); //Inverse of View Space matrix is World space matrix XMVECTOR worldSpaceNear = XMVector3TransformCoord(cameraSpaceNear, invMat); XMVECTOR worldSpaceFar = XMVector3TransformCoord(cameraSpaceFar, invMat); pickRayInWorldSpacePos = worldSpaceNear; pickRayInWorldSpaceDir = worldSpaceFar-worldSpaceNear; pickRayInWorldSpaceDir = XMVector3Normalize(pickRayInWorldSpaceDir); } A couple of notes: The mouse coordinates are already converted so that the top left corner of the client window would be (0,0) and the bottom rigth (800,600) ( or whatever resolution you would have) I hadn't used any far or near plane before, so i just made some arbitrary number up for them. To my understanding it shouldnt matter as long as the object you are trying to pick is in between the range of thoese numbers The viewAngle is the same angle that I used when setting the camera view with XMMatrixPerspectiveFovLH , I just hadn't made it a member variable of my Camera class yet. I removed the variable aspectRation and zoomFactor because I assumed that they where related to some specific function of his game. Now I'm not sure, but I think the problems lies either withing the mouse to viewspace conversion, maby that we use diffrent coordinations systems. Either that or how i transform the matrixes in the the end, because i know order is important when it comes to matrixes. Any help is appriciated! Thanks in advance. Edit: One more note, my code is in c++

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  • XNA - 3D AABB collision detection and response

    - by fastinvsqrt
    I've been fiddling around with 3D AABB collision in my voxel engine for the last couple of days, and every method I've come up with thus far has been almost correct, but each one never quite worked exactly the way I hoped it would. Currently what I do is get two bounding boxes for my entity, one modified by the X translation component and the other by the Z component, and check if each collides with any of the surrounding chunks (chunks have their own octrees that are populated only with blocks that support collision). If there is a collision, then I cast out rays into that chunk to get the shortest collision distance, and set the translation component to that distance if the component is greater than the distance. The problem is that sometimes collisions aren't even registered. Here's a video on YouTube that I created showing what I mean. I suspect the problem may be with the rays that I cast to get the collision distance not being where I think they are, but I'm not entirely sure what would be wrong with them if they are indeed the problem. Here is my code for collision detection and response in the X direction (the Z direction is basically the same): // create the XZ offset vector Vector3 offsXZ = new Vector3( ( _translation.X > 0.0f ) ? SizeX / 2.0f : ( _translation.X < 0.0f ) ? -SizeX / 2.0f : 0.0f, 0.0f, ( _translation.Z > 0.0f ) ? SizeZ / 2.0f : ( _translation.Z < 0.0f ) ? -SizeZ / 2.0f : 0.0f ); // X physics BoundingBox boxx = GetBounds( _translation.X, 0.0f, 0.0f ); if ( _translation.X > 0.0f ) { foreach ( Chunk chunk in surrounding ) { if ( chunk.Collides( boxx ) ) { float dist = GetShortestCollisionDistance( chunk, Vector3.Right, offsXZ ) - 0.0001f; if ( dist < _translation.X ) { _translation.X = dist; } } } } else if ( _translation.X < 0.0f ) { foreach ( Chunk chunk in surrounding ) { if ( chunk.Collides( boxx ) ) { float dist = GetShortestCollisionDistance( chunk, Vector3.Left, offsXZ ) - 0.0001f; if ( dist < -_translation.X ) { _translation.X = -dist; } } } } And here is my implementation for GetShortestCollisionDistance: private float GetShortestCollisionDistance( Chunk chunk, Vector3 rayDir, Vector3 offs ) { int startY = (int)( -SizeY / 2.0f ); int endY = (int)( SizeY / 2.0f ); int incY = (int)Cube.Size; float dist = Chunk.Size; for ( int y = startY; y <= endY; y += incY ) { // Position is the center of the entity's bounding box Ray ray = new Ray( new Vector3( Position.X + offs.X, Position.Y + offs.Y + y, Position.Z + offs.Z ), rayDir ); // Chunk.GetIntersections(Ray) returns Dictionary<Block, float?> foreach ( var pair in chunk.GetIntersections( ray ) ) { if ( pair.Value.HasValue && pair.Value.Value < dist ) { dist = pair.Value.Value; } } } return dist; } I realize some of this code can be consolidated to help with speed, but my main concern right now is to get this bit of physics programming to actually work.

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  • sql: can i do a max(count(*)) ?

    - by every_answer_gets_a_point
    here's my code: select yr,count(*) from movie join casting on casting.movieid=movie.id join actor on casting.actorid = actor.id where actor.name = 'John Travolta' group by yr here's the question Which were the busiest years for 'John Travolta'. Show the number of movies he made for each year. here's the table structure movie(id, title, yr, score, votes, director) actor(id, name) casting(movieid, actorid, ord) this is the output i am getting: yr count(*) 1976 1 1977 1 1978 1 1981 1 1994 1 etcetc i need to get the rows for which count(*) is max how do i do this?

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  • sql - HAVING at least 10

    - by every_answer_gets_a_point
    i would like to display results for values that are only 10 and over select name, count(*) from actor join casting on casting.actorid = actor.id where casting.ord = 1 group by name order by 2 desc that will return this: name count(*) Sean Connery 19 Harrison Ford 19 Robert De Niro 18 Sylvester Stallone 18 etc but i want to return values of count(*) that are only above 10 how do i do this? with having?

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  • Project-Based ERP - The Evolution of Project Managemen

    Fred Studer speaks with Ray Wang, Principal Analyst at Forrester Research and Ted Kempf, Senior Director for Oracle's Project Management Solutions about trends in the project management market, where enterprise project management is heading in the next 2 - 3 years and highlights from Ray's new line of research on project management solutions.

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  • Calculating 2D (screen) coordinates from 3D positions in XNA 4.0

    - by NDraskovic
    I have a program that draws some items to the scene by loading their positions from a file. Now I want to place a Ray on the same location where the items are drawn. So my question is how can I calculate the position of the ray (it's 2D components) by using 3D coordinates of each particular item? The items don't move anywhere, so once they are placed they stay until the end of the programs execution. Thanks.

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  • Are these non-standard applications of rendering practical in games?

    - by maul
    I've recently got into 3D and I came up with a few different "tricky" rendering techniques. Unfortunately I don't have the time to work on this myself, but I'd like to know if these are known methods and if they can be used in practice. Hybrid rendering Now I know that ray-tracing is still not fast enough for real-time rendering, at least on home computers. I also know that hybrid rendering (a combination of rasterization and ray-tracing) is a well known theory. However I had the following idea: one could separate a scene into "important" and "not important" objects. First you render the "not important" objects using traditional rasterization. In this pass you also render the "important" objects using a special shader that simply marks these parts on the image using a special color, or some stencil/depth buffer trickery. Then in the second pass you read back the results of the first pass and start ray tracing, but only from the pixels that were marked by the "important" object's shader. This would allow you to only ray-trace exactly what you need to. Could this be fast enough for real-time effects? Rendered physics I'm specifically talking about bullet physics - intersection of a very small object (point/bullet) that travels across a straight line with other, relatively slow-moving, fairly constant objects. More specifically: hit detection. My idea is that you could render the scene from the point of view of the gun (or the bullet). Every object in the scene would draw a different color. You only need to render a 1x1 pixel window - the center of the screen (again, from the gun's point of view). Then you simply check that central pixel and the color tells you what you hit. This is pixel-perfect hit detection based on the graphical representation of objects, which is not common in games. Afaik traditional OpenGL "picking" is a similar method. This could be extended in a few ways: For larger (non-bullet) objects you render a larger portion of the screen. If you put a special-colored plane in the middle of the scene (exactly where the bullet will be after the current frame) you get a method that works as the traditional slow-moving iterative physics test as well. You could simulate objects that the bullet can pass through (with decreased velocity) using alpha blending or some similar trick. So are these techniques in use anywhere, and/or are they practical at all?

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  • Google Chromecast cast tab from Chrome browser sucks

    - by Ken Hortsch
    Originally posted on: http://geekswithblogs.net/BlueProbe/archive/2013/07/28/153537.aspxOk so I know it’s in beta.  And I should have known when I watched the Nexus 7 and Chromecast press event and the demo showed the browser casting a slide show.  But, when I bought one of these little $35 beauties and tried casting a soccer game from ESPN it was pathetic with a 2 FPS rate.  Netflix and YouTube are awesome.  We’ll see what we get out of beta.

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  • Win Server 2k and Win 7 client

    - by Ray Kruse
    I have a Win Server 2000 system with AD configured. The network consists of an OKI printer, a network server, a wifi router a Win 2k client and the server. I'm trying to connect a Win 7 client. The purpose of the network, besides sharing equipment is to move files from client to client and scatter backups over more than 1 machine. The Win 7 client is configured for DHCP and does in fact receive it's IP and DNS configuration from the server and it sees the printer, wifi router and network drive, but does not see the Win 2k client nor the Win 2k server. I have tried the LAN Management Authentication Level set to 'Send LM & NTLM responses' with the 128 bit encryption removed. I've also done the registry hack on the key 'LmCompatibilityLevel'. Neither of these have helped. I have two questions: Is there a fix or is Win 2k totally incompatible? Is the best (or quickest/cheapest) fix to upgrade the server to Win 2k3 and not worry about the Win 2k client? Thanks for any help. Ray Kruse Buffalo, KY

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  • GLSL Atmospheric Scattering Issue

    - by mtf1200
    I am attempting to use Sean O'Neil's shaders to accomplish atmospheric scattering. For now I am just using SkyFromSpace and GroundFromSpace. The atmosphere works fine but the planet itself is just a giant dark sphere with a white blotch that follows the camera. I think the problem might rest in the "v3Attenuation" variable as when this is removed the sphere is show (albeit without scattering). Here is the vertex shader. Thanks for the time! uniform mat4 g_WorldViewProjectionMatrix; uniform mat4 g_WorldMatrix; uniform vec3 m_v3CameraPos; // The camera's current position uniform vec3 m_v3LightPos; // The direction vector to the light source uniform vec3 m_v3InvWavelength; // 1 / pow(wavelength, 4) for the red, green, and blue channels uniform float m_fCameraHeight; // The camera's current height uniform float m_fCameraHeight2; // fCameraHeight^2 uniform float m_fOuterRadius; // The outer (atmosphere) radius uniform float m_fOuterRadius2; // fOuterRadius^2 uniform float m_fInnerRadius; // The inner (planetary) radius uniform float m_fInnerRadius2; // fInnerRadius^2 uniform float m_fKrESun; // Kr * ESun uniform float m_fKmESun; // Km * ESun uniform float m_fKr4PI; // Kr * 4 * PI uniform float m_fKm4PI; // Km * 4 * PI uniform float m_fScale; // 1 / (fOuterRadius - fInnerRadius) uniform float m_fScaleDepth; // The scale depth (i.e. the altitude at which the atmosphere's average density is found) uniform float m_fScaleOverScaleDepth; // fScale / fScaleDepth attribute vec4 inPosition; vec3 v3ELightPos = vec3(g_WorldMatrix * vec4(m_v3LightPos, 1.0)); vec3 v3ECameraPos= vec3(g_WorldMatrix * vec4(m_v3CameraPos, 1.0)); const int nSamples = 2; const float fSamples = 2.0; varying vec4 color; float scale(float fCos) { float x = 1.0 - fCos; return m_fScaleDepth * exp(-0.00287 + x*(0.459 + x*(3.83 + x*(-6.80 + x*5.25)))); } void main(void) { gl_Position = g_WorldViewProjectionMatrix * inPosition; // Get the ray from the camera to the vertex and its length (which is the far point of the ray passing through the atmosphere) vec3 v3Pos = vec3(g_WorldMatrix * inPosition); vec3 v3Ray = v3Pos - v3ECameraPos; float fFar = length(v3Ray); v3Ray /= fFar; // Calculate the closest intersection of the ray with the outer atmosphere (which is the near point of the ray passing through the atmosphere) float B = 2.0 * dot(m_v3CameraPos, v3Ray); float C = m_fCameraHeight2 - m_fOuterRadius2; float fDet = max(0.0, B*B - 4.0 * C); float fNear = 0.5 * (-B - sqrt(fDet)); // Calculate the ray's starting position, then calculate its scattering offset vec3 v3Start = m_v3CameraPos + v3Ray * fNear; fFar -= fNear; float fDepth = exp((m_fInnerRadius - m_fOuterRadius) / m_fScaleDepth); float fCameraAngle = dot(-v3Ray, v3Pos) / fFar; float fLightAngle = dot(v3ELightPos, v3Pos) / fFar; float fCameraScale = scale(fCameraAngle); float fLightScale = scale(fLightAngle); float fCameraOffset = fDepth*fCameraScale; float fTemp = (fLightScale + fCameraScale); // Initialize the scattering loop variables float fSampleLength = fFar / fSamples; float fScaledLength = fSampleLength * m_fScale; vec3 v3SampleRay = v3Ray * fSampleLength; vec3 v3SamplePoint = v3Start + v3SampleRay * 0.5; // Now loop through the sample rays vec3 v3FrontColor = vec3(0.0, 0.0, 0.0); vec3 v3Attenuate; for(int i=0; i<nSamples; i++) { float fHeight = length(v3SamplePoint); float fDepth = exp(m_fScaleOverScaleDepth * (m_fInnerRadius - fHeight)); float fScatter = fDepth*fTemp - fCameraOffset; v3Attenuate = exp(-fScatter * (m_v3InvWavelength * m_fKr4PI + m_fKm4PI)); v3FrontColor += v3Attenuate * (fDepth * fScaledLength); v3SamplePoint += v3SampleRay; } vec3 first = v3FrontColor * (m_v3InvWavelength * m_fKrESun + m_fKmESun); vec3 secondary = v3Attenuate; color = vec4((first + vec3(0.25,0.25,0.25) * secondary), 1.0); // ^^ that color is passed to the frag shader and is used as the gl_FragColor } Here is also an image of the problem image

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  • Not getting desired results with SSAO implementation

    - by user1294203
    After having implemented deferred rendering, I tried my luck with a SSAO implementation using this Tutorial. Unfortunately, I'm not getting anything that looks like SSAO, you can see my result below. You can see there is some weird pattern forming and there is no occlusion shading where there needs to be (i.e. in between the objects and on the ground). The shaders I implemented follow: #VS #version 330 core uniform mat4 invProjMatrix; layout(location = 0) in vec3 in_Position; layout(location = 2) in vec2 in_TexCoord; noperspective out vec2 pass_TexCoord; smooth out vec3 viewRay; void main(void){ pass_TexCoord = in_TexCoord; viewRay = (invProjMatrix * vec4(in_Position, 1.0)).xyz; gl_Position = vec4(in_Position, 1.0); } #FS #version 330 core uniform sampler2D DepthMap; uniform sampler2D NormalMap; uniform sampler2D noise; uniform vec2 projAB; uniform ivec3 noiseScale_kernelSize; uniform vec3 kernel[16]; uniform float RADIUS; uniform mat4 projectionMatrix; noperspective in vec2 pass_TexCoord; smooth in vec3 viewRay; layout(location = 0) out float out_AO; vec3 CalcPosition(void){ float depth = texture(DepthMap, pass_TexCoord).r; float linearDepth = projAB.y / (depth - projAB.x); vec3 ray = normalize(viewRay); ray = ray / ray.z; return linearDepth * ray; } mat3 CalcRMatrix(vec3 normal, vec2 texcoord){ ivec2 noiseScale = noiseScale_kernelSize.xy; vec3 rvec = texture(noise, texcoord * noiseScale).xyz; vec3 tangent = normalize(rvec - normal * dot(rvec, normal)); vec3 bitangent = cross(normal, tangent); return mat3(tangent, bitangent, normal); } void main(void){ vec2 TexCoord = pass_TexCoord; vec3 Position = CalcPosition(); vec3 Normal = normalize(texture(NormalMap, TexCoord).xyz); mat3 RotationMatrix = CalcRMatrix(Normal, TexCoord); int kernelSize = noiseScale_kernelSize.z; float occlusion = 0.0; for(int i = 0; i < kernelSize; i++){ // Get sample position vec3 sample = RotationMatrix * kernel[i]; sample = sample * RADIUS + Position; // Project and bias sample position to get its texture coordinates vec4 offset = projectionMatrix * vec4(sample, 1.0); offset.xy /= offset.w; offset.xy = offset.xy * 0.5 + 0.5; // Get sample depth float sample_depth = texture(DepthMap, offset.xy).r; float linearDepth = projAB.y / (sample_depth - projAB.x); if(abs(Position.z - linearDepth ) < RADIUS){ occlusion += (linearDepth <= sample.z) ? 1.0 : 0.0; } } out_AO = 1.0 - (occlusion / kernelSize); } I draw a full screen quad and pass Depth and Normal textures. Normals are in RGBA16F with the alpha channel reserved for the AO factor in the blur pass. I store depth in a non linear Depth buffer (32F) and recover the linear depth using: float linearDepth = projAB.y / (depth - projAB.x); where projAB.y is calculated as: and projAB.x as: These are derived from the glm::perspective(gluperspective) matrix. z_n and z_f are the near and far clip distance. As described in the link I posted on the top, the method creates samples in a hemisphere with higher distribution close to the center. It then uses random vectors from a texture to rotate the hemisphere randomly around the Z direction and finally orients it along the normal at the given pixel. Since the result is noisy, a blur pass follows the SSAO pass. Anyway, my position reconstruction doesn't seem to be wrong since I also tried doing the same but with the position passed from a texture instead of being reconstructed. I also tried playing with the Radius, noise texture size and number of samples and with different kinds of texture formats, with no luck. For some reason when changing the Radius, nothing changes. Does anyone have any suggestions? What could be going wrong?

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