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  • How to find a random point in a quadrangle?

    - by Gregg Cleland
    Hi! I have to be able to set a random location for a waypoint for a flight sim. The maths challenge is straightforward: "To find a single random location within a quadrangle, where there's an equal chance of the point being at any location." Visually like this: http://screencast.com/t/NTUxMzJhZGQ An example ABCD quadrangle is: A:[21417.78 37105.97] B:[38197.32 24009.74] C:[1364.19 2455.54] D:[1227.77 37378.81] Thanks in advance for any help you can provide. :-)

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  • minimum enclosing rectangle of fixed aspect ratio

    - by Ramya Narasimha
    I have an Image with many rectangles at different positions in the image and of different sizes (both overlapping and non-overlapping). I also have a non-negative scores associated with each of these rectangles. My problem now is to find one larger rectangle *of a fixed (given) aspect ratio* that encloses as many of these rectangles as possible. I am looking for an algorithm to do this, if anyone has a solution, even a partial one it would be helpful. Please note that the positions of the rectangles in the image is fixed and cannot be moved around and there is no orientation issue as all of them are upright.

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  • Fitting maximum amount of shapes on a surface

    - by Fuu
    In industry, there is often a problem where you need to calculate the most efficient use of material, be it fabric, wood, metal etc. So the starting point is X amount of shapes of given dimensions, made out of polygons and/or curved lines, and target is another polygon of given dimensions. I assume many of the current CAM suites implement this, but having no experience using them or of their internals, what kind of computational algorithm is used to find the most efficient use of space? Can someone point me to a book or other reference that discusses this subject?

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  • Construct A Polygon Out of Union of Many Polygons

    - by Ngu Soon Hui
    Supposed that I have many polygons, what is the best algorithm to construct a polygon--maybe with holes- out of the union of all those polygons? For my purpose, you can imagine each piece of a polygon as a jigsaw puzzle piece, when you complete them you will get a nice picture. But the catch is that a small portion <5% of the jigsaw is missing, and you are still require to form a picture as complete as possible; that's the polygon-- maybe with holes-- that I want to form. My naive approach is to take two polygons, union them, and take another polygon, union it with the union of the two polygons, and repeat this process until every single piece is union. Then I will run through the union polygon list and check whether there are still some polygons can be combined, and I will repeat this process until a satisfactory result is achieved. But this seems to be like an extremely naive approach. I just wonder is there any other better algorithm?

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  • Detecting the axis of rotation from a pointcloud

    - by tfinniga
    I'm trying to auto-detect the axis of rotation on a 3d pointcloud. In other words, if I took a small 3d pointcloud, chose a single axis of rotation, and make several copies of the points at different rotation angles, then I get a larger pointcloud. The input to my algorithm is the larger pointcloud, and the desired output is the single axis of symmetry. And eventually I'm going to compute the correspondences between points that are rotations of each other. The size of the larger pointcloud is on the order of 100K points, and the number of rotational copies made is unknown. The rotation angles in my case have constant deltas, but don't necessarily span 360 degrees. For example, I might have 0, 20, 40, 60. Or I might have 0, 90, 180, 270. But I won't have 0, 13, 78, 212 (or if I do, I don't care to detect it). This seems like a computer vision problem, but I'm having trouble figuring out how to precisely find the axis. The input will generally be very clean, close to float accuracy.

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  • Problems implementing a screen space shadow ray tracing shader

    - by Grieverheart
    Here I previously asked for the possibility of ray tracing shadows in screen space in a deferred shader. Several problems were pointed out. One of the most important problem is that only visible objects can cast shadows and objects between the camera and the shadow caster can interfere. Still I thought it'd be a fun experiment. The idea is to calculate the view coordinates of pixels and cast a ray to the light. The ray is then traced pixel by pixel to the light and its depth is compared with the depth at the pixel. If a pixel is in front of the ray, a shadow is casted at the original pixel. At first I thought that I could use the DDA algorithm in 2D to calculate the distance 't' (in p = o + t d, where o origin, d direction) to the next pixel and use it in the 3D ray equation to find the ray's z coordinate at that pixel's position. For the 2D ray, I would use the projected and biased 3D ray direction and origin. The idea was that 't' would be the same in both 2D and 3D equations. Unfortunately, this is not the case since the projection matrix is 4D. Thus, some tweak needs to be done to make this work this way. I would like to ask if someone knows of a way to do what I described above, i.e. from a 2D ray in texture coordinate space to get the 3D ray in screen space. I did implement a simple version of the idea which you can see in the following video: video here Shadows may seem a bit pixelated, but that's mostly because of the size of the step in 't' I chose. And here is the shader: #version 330 core uniform sampler2D DepthMap; uniform vec2 projAB; uniform mat4 projectionMatrix; const vec3 light_p = vec3(-30.0, 30.0, -10.0); 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; } void main(void){ vec3 origin = CalcPosition(); if(origin.z < -60) discard; vec2 pixOrigin = pass_TexCoord; //tex coords vec3 dir = normalize(light_p - origin); vec2 texel_size = vec2(1.0 / 600.0); float t = 0.1; ivec2 pixIndex = ivec2(pixOrigin / texel_size); out_AO = 1.0; while(true){ vec3 ray = origin + t * dir; vec4 temp = projectionMatrix * vec4(ray, 1.0); vec2 texCoord = (temp.xy / temp.w) * 0.5 + 0.5; ivec2 newIndex = ivec2(texCoord / texel_size); if(newIndex != pixIndex){ float depth = texture(DepthMap, texCoord).r; float linearDepth = projAB.y / (depth - projAB.x); if(linearDepth > ray.z + 0.1){ out_AO = 0.2; break; } pixIndex = newIndex; } t += 0.5; if(texCoord.x < 0 || texCoord.x > 1.0 || texCoord.y < 0 || texCoord.y > 1.0) break; } } As you can see, here I just increment 't' by some arbitrary factor, calculate the 3D ray and project it to get the pixel coordinates, which is not really optimal. Hopefully, I would like to optimize the code as much as possible and compare it with shadow mapping and how it scales with the number of lights. PS: Keep in mind that I reconstruct position from depth by interpolating rays through a full screen quad.

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  • assigning values to shader parameters in the XNA content pipeline

    - by Nick
    I have tried creating a simple content processor that assigns the custom effect I created to models instead of the default BasicEffect. [ContentProcessor(DisplayName = "Shadow Mapping Model")] public class ShadowMappingModelProcessor : ModelProcessor { protected override MaterialContent ConvertMaterial(MaterialContent material, ContentProcessorContext context) { EffectMaterialContent shadowMappingMaterial = new EffectMaterialContent(); shadowMappingMaterial.Effect = new ExternalReference<EffectContent>("Effects/MultipassShadowMapping.fx"); return context.Convert<MaterialContent, MaterialContent>(shadowMappingMaterial, typeof(MaterialProcessor).Name); } } This works, but when I go to draw a model in a game, the effect has no material properties assigned. How would I go about assigning, say, my DiffuseColor or SpecularColor shader parameter to white or (better) can I assign it to some value specified by the artist in the model? (I think this may have something to do with the OpaqueDataDictionary but I am confused on how to use it--the content pipeline has always been a black box to me.)

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  • Shader inputs in a general purpose engine

    - by dreta
    I'm not familiar with SDKs like Unity or UDK that much, so i can't check this offhand. Do general purpose engines allow users to create custom uniform variables? The way i see it, and the way i have implemented it in an engine i'm writing to learn 3D, is that there is a "set" of uniforms provided by the engine and if you want to write a custom shader then you utilize uniforms you need to create a wanted effect. Now, the thing is, first of all i'm not an artist, second of all, i didn't have a chance to create complex scenes yet. So my question is, is it common practice to define variables that the engine provides and only allow the user to work with what they're given? Allowing users to add custom programs and use them where they want is not hard, but i have issues imagining how you'd go about doing the same for uniforms.

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  • HLSL Pixel Shader that does palette swap

    - by derrace
    I have implemented a simple pixel shader which can replace a particular colour in a sprite with another colour. It looks something like this: sampler input : register(s0); float4 PixelShaderFunction(float2 coords: TEXCOORD0) : COLOR0 { float4 colour = tex2D(input, coords); if(colour.r == sourceColours[0].r && colour.g == sourceColours[0].g && colour.b == sourceColours[0].b) return targetColours[0]; return colour; } What I would like to do is have the function take in 2 textures, a default table, and a lookup table (both same dimensions). Grab the current pixel, and find the location XY (coords) of the matching RGB in the default table, and then substitute it with the colour found in the lookup table at XY. I have figured how to pass the Textures from C# into the function, but I am not sure how to find the coords in the default table by matching the colour. Could someone kindly assist? Thanks in advance.

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  • Low complexity shader to indicate the sides of a polyline

    - by Pris
    I have a bunch of polylines that I draw using GL_LINES. They can have thousands of points. They actually represent the separation of land and water on a map. I don't have complete polygons, just the ordered set of points. I'm looking for a neat but efficient way to visually convey Side A and Side B as being different. For example I could offset the polyline in one direction a few times and fade it out (but every offset is doubling the number of points), or offset it once to make a "ribbon" and give one side a 'glow' like effect to mimic the outer glow or shadow of a polygon). This is for a mobile application and I'm using OpenGL ES 2. I'd like to keep the effect as simple as possible from a complexity stand point. I'm looking for some additional ideas; maybe there's a clever shader technique out there or a visual effect I haven't considered.

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  • DX11 - Weird shader behavior with and without branching

    - by Martin Perry
    I have found problem in my shader code, which I dont´t know how to solve. I want to rewrite this code without "ifs" tmp = evaluate and result is 0 or 1 (nothing else) if (tmp == 1) val = X1; if (tmp == 0) val = X2; I rewite it this way, but this piece of code doesn ´t word correctly tmp = evaluate and result is 0 or 1 (nothing else) val = tmp * X1 val = !tmp * X2 However if I change it to: tmp = evaluate and result is 0 or 1 (nothing else) val = tmp * X1 if (!tmp) val = !tmp * X2 It works fine... but it is useless because of "if", which need to be eliminated I honestly don´t understand it Posted Image . I tried compilation with NO and FULL optimalization, result is same

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  • Shader inputs in a general purpouse engine

    - by dreta
    I'm not familiar with SDKs like Unity or UDK that much, so i can't check this off hand. Do general purpouse engines allow users to create custom uniform variables? The way i see it, and the way i have implemented it in an engine i'm writing to learn 3D, is that there is a "set" of uniforms provided by the engine and if you want to write a custom shader then you utilize uniforms you need to create a wanted effect. Now, the thing is, first of all i'm not an artist, second of all, i didn't have a chance to create complex scenes yet. So my question is, is it common practice to define variables that the engine provides and only allow the user to work with what they're given? Allowing users to add custom programs and use them where they want is not hard, but i have issues imagining how you'd go about doing the same for uniforms.

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  • fragment shader directional light positioning with camera

    - by meWantToLearn
    Im trying to set up directional lighting in the fragment shader. So the direction of my light moves with the camera position. #version 150 core uniform sampler2D diffuseTex; uniform vec4 lightColour; uniform vec3 lightDirection; vec3 LNorm = normalize(lightDirection); vec3 normal = normalize(IN.normal); vec3 calColour = lightColour[i].rgb * intensity; gl_FragColor = vec4(diffuse.rbg * calColour, diffuse.a); It lights the entire scene.

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  • Shader Model 3.0 not available

    - by Romy
    I have Acer 4745G with ATI HD 5650 1GB VRAM. After I installed the COD Black Ops trough Wine Playonlinux and successfully installed, and I play the game and then appear message "Shader Model 3.0 not available". I have installed ATI driver 11.8 when I trying this game. And then I'm trying to install the driver from menu "System Administration Additional Driver, it doesn't work. I cannot log in, in the screen appear only the text for log in. And then I uninstall it trough recovery mode. And then I download ATI driver 11.11 from official ATI/AMD website, and then I restart my computer and my screen appearing only text again. I'm using Ubuntu (Ultimate Edition) 11.04. How to overcome this problem?

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  • Some help understanding and modifying a 2D shader

    - by electroflame
    I have a similar question as the one posed here, except that I don't wish to use a 1D Color Palette. I simply wish to have it display 1 color of my choosing (red, for example). I plan to use this as a "shield" effect for a 2D ship. I also wish to understand how it works a little bit better, as I'll be the first to admit that shaders in general are not my strongest suit. I'm not asking for an overview of HLSL (as that is too broad of a subject), just an explanation of how this shader works, and the best way to implement it in a 2D game. Code examples would be ideal (even if they are theoretical) but if the answer is explained well enough, I might be able to manage with plain old text. This is also in XNA 4.0. Thanks in advance.

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  • Writing a basic shader for large input files

    - by Zoltan Varadi
    I started writing a shader for my iOS app and instead of starting from scratch i used this tutorial here: http://www.raywenderlich.com/3664/opengl-es-2-0-for-iphone-tutorial I wrote an import function, first to import wavefront .obj models. My problem is that with I can't handle larger inputs (with a simple cube it was working). I realized that the indices array is an array of GLubyte values, which is unsigned char, so as a result i cant have more than 256 indexes. I modified it to GLuint, but then only get a blank screen. What else needs to me modified? p.s.: the source can be downloaded from here: http://d1xzuxjlafny7l.cloudfront.net/downloads/HelloOpenGL.zip

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  • How to read verbose VC++ linker output

    - by Assaf Lavie
    Trying to debug some linker errors, I turned on /VERBOSE and I'm trying to make sense of the output. It occurs to me that I really don't know how to read it. For example: 1>Compiling version info 1>Linking... 1>Starting pass 1 1>Processed /DEFAULTLIB:mfc80.lib 1>Processed /DEFAULTLIB:mfcs80.lib 1>Processed /DEFAULTLIB:msvcrt.lib 1>Processed /DEFAULTLIB:kernel32.lib 1>Processed /DEFAULTLIB:user32.lib .... 1>Processed /DEFAULTLIB:libgslcblasMD.lib 1>Searching libraries 1> Searching V:\Src\Solutions\\..\..\\Common\Win32\Lib\PlxApi.lib: 1> Searching ..\..\..\..\out\win32\release\lib\camerageometry.lib: 1> Searching ..\..\..\..\out\win32\release\lib\geometry.lib: 1> Found "public: __thiscall VisionMap::Geometry::Box2d::operator class VisionMap::Geometry::Box2DInt(void)const " (??BBox2d@Geometry@VisionMap@@QBE?AVBox2DInt@12@XZ) 1> Referenced in FocusDlg.obj 1> Loaded geometry.lib(Box2d.obj) 1>Processed /DEFAULTLIB:CGAL-vc80-mt.lib 1>Processed /DEFAULTLIB:boost_thread-vc80-mt-1_33_1.lib What's going on here? I think I understand this bit: 1>Processed /DEFAULTLIB:libgslcblasMD.lib 1>Searching libraries 1> Searching V:\Src\Solutions\\..\..\\Common\Win32\Lib\PlxApi.lib: 1> Searching ..\..\..\..\out\win32\release\lib\camerageometry.lib: 1> Searching ..\..\..\..\out\win32\release\lib\geometry.lib: 1> Found "public: __thiscall VisionMap::Geometry::Box2d::operator class VisionMap::Geometry::Box2DInt(void)const " (??BBox2d@Geometry@VisionMap@@QBE?AVBox2DInt@12@XZ) 1> Referenced in FocusDlg.obj 1> Loaded geometry.lib(Box2d.obj) It's trying to find the implementation of the above operator, which is used somewhere in FocusDlg.cpp, and it finds it in geometry.lib. But what does 1>Processed /DEFAULTLIB:libgslcblasMD.lib mean? What determines the order of symbol resolution? Why is it loading this particular symbol while processing libgslcblasMD.lib which is a 3rd party library? Or am I reading it wrong? It seems that the linker is going through the symbols referenced in the project's various object files, but I have no idea in what order. It then searches the static libraries the project uses - by project reference, explicit import and automatic default library imports; but it does so in an order that, again, seems arbitrary to me. When it finds a symbol, for example in geometry.lib, it then continues to find a bunch of other symbols from the same lib: 1> Searching V:\Src\Solutions\\..\..\\Common\Win32\Lib\PlxApi.lib: 1> Searching ..\..\..\..\out\win32\release\lib\camerageometry.lib: 1> Searching ..\..\..\..\out\win32\release\lib\geometry.lib: 1> Found "public: __thiscall VisionMap::Geometry::Box2d::operator class VisionMap::Geometry::Box2DInt(void)const " (??BBox2d@Geometry@VisionMap@@QBE?AVBox2DInt@12@XZ) 1> Referenced in FocusDlg.obj 1> Loaded geometry.lib(Box2d.obj) 1>Processed /DEFAULTLIB:CGAL-vc80-mt.lib 1>Processed /DEFAULTLIB:boost_thread-vc80-mt-1_33_1.lib 1> Found "public: __thiscall VisionMap::Geometry::Box2DInt::Box2DInt(int,int,int,int)" (??0Box2DInt@Geometry@VisionMap@@QAE@HHHH@Z) 1> Referenced in FocusDlg.obj 1> Referenced in ImageView.obj 1> Referenced in geometry.lib(Box2d.obj) 1> Loaded geometry.lib(Box2DInt.obj) 1> Found "public: virtual __thiscall VisionMap::Geometry::Point3d::~Point3d(void)" (??1Point3d@Geometry@VisionMap@@UAE@XZ) 1> Referenced in GPSFrm.obj 1> Referenced in MainFrm.obj 1> Loaded geometry.lib(Point3d.obj) 1> Found "void __cdecl VisionMap::Geometry::serialize<class boost::archive::binary_oarchive>(class boost::archive::binary_oarchive &,class VisionMap::Geometry::Point3d &,unsigned int)" (??$serialize@Vbinary_oarchive@archive@boost@@@Geometry@VisionMap@@YAXAAVbinary_oarchive@archive@boost@@AAVPoint3d@01@I@Z) 1> Referenced in GPSFrm.obj 1> Referenced in MainFrm.obj 1> Loaded geometry.lib(GeometrySerializationImpl.obj) But then, for some reason, it goes on to find symbols that are defined in other libs, and returns to geometry later on (a bunch of times). So clearly it's not doing "look in geometry and load every symbol that's references in the project, and then continue to other libraries". But it's not clear to me what is the order of symbol lookup. And what's the deal with all those libraries being processed at the beginning of the linker's work, but not finding any symbols to load from them? Does this project really not use anything from msvcrt.lib, kernel32.lib? Seems unlikely. So basically I'm looking to decipher the underlying order in the linker's operation.

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  • Why is a fully transparent pixel still rendered?

    - by Mr Bell
    I am trying to make a pixel shader that achieves an effect similar to this video http://www.youtube.com/watch?v=f1uZvurrhig&feature=related My basic idea is render the scene to a temp render target then Render the previously rendered image with a slight fade on to another temp render target Draw the current scene on top of that Draw the results on to a render target that persists between draws Draw the results on to the screen But I am having problems with the fading portion. If I have my pixel shader return a color with its A component set to 0, shouldn't that basically amount to drawing nothing? (Assuming that sprite batch blend mode is set to AlphaBlend) To test this I have my pixel shader return a transparent red color. Instead of nothing being drawn, it draws a partially transparent red box. I hope that my question makes sense, but if it doesnt please ask me to clarify Here is the drawing code public override void Draw(GameTime gameTime) { GraphicsDevice.SamplerStates[1] = SamplerState.PointWrap; drawImageOnClearedRenderTarget(presentationTarget, tempRenderTarget, fadeEffect); drawImageOnRenderTarget(sceneRenderTarget, tempRenderTarget); drawImageOnClearedRenderTarget(tempRenderTarget, presentationTarget); GraphicsDevice.SetRenderTarget(null); drawImage(backgroundTexture); drawImage(presentationTarget); base.Draw(gameTime); } private void drawImage(Texture2D image, Effect effect = null) { spriteBatch.Begin(0, BlendState.AlphaBlend, SamplerState.PointWrap, null, null, effect); spriteBatch.Draw(image, new Rectangle(0, 0, width, height), Color.White); spriteBatch.End(); } private void drawImageOnRenderTarget(Texture2D image, RenderTarget2D target, Effect effect = null) { GraphicsDevice.SetRenderTarget(target); drawImage(image, effect); } private void drawImageOnClearedRenderTarget(Texture2D image, RenderTarget2D target, Effect effect = null) { GraphicsDevice.SetRenderTarget(target); GraphicsDevice.Clear(Color.Transparent); drawImage(image, effect); } Here is the fade pixel shader sampler TextureSampler : register(s0); float4 PixelShaderFunction(float2 texCoord : TEXCOORD0) : COLOR0 { float4 c = 0; c = tex2D(TextureSampler, texCoord); //c.a = clamp(c.a - 0.05, 0, 1); c.r = 1; c.g = 0; c.b = 0; c.a = 0; return c; } technique Fade { pass Pass1 { PixelShader = compile ps_2_0 PixelShaderFunction(); } }

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  • Doubt about texture waves in CG Ocean Shader

    - by Alexandre
    I'm new on graphical programming, and I'm having some trouble understanding the Ocean Shader described on "Effective Water Simulation from Physical Models" from GPU Gems. The source code associated to this article is here. My problem has been to understand the concept of texture waves. First of all, what is achieved by texture waves? I'm having a hard time trying to figure out it's usefulness. In the section 1.2.4 of the article, it does say that the waves summed into the texture have the same parametrization as the waves used for vertex positioning. Does it mean that I can't use the texture provided by the source code if I change the parameters of the waves, or add more waves to sum? And in the section 1.4.1, is said that we can assume that there is no rotation between texture space and world space if the texture coordinates for our normal map are implicit. What does mean that the "normal map are implicit'? And why do I need a rotation between texture and world spaces if the normal map are not implicit? I would be very grateful for any help on this.

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  • Developing geometry-based Web Services for WebLogic | Part 1 by Ronald van Luttikhuizen

    - by JuergenKress
    In a recent project we developed Web Services that expose geographical data in their operations. This blog explains the use case for the service, gives an overview of the software architecture, and briefly discusses GML as markup language for geographical data. Part 2 of this blog provides pointers on the implementation of the service while part 3 discusses the deployment on Oracle WebLogic Server. Use Case The "BAG" (Basisregistratie Adressen en Gebouwen) is a Dutch national database containing information on all addresses and buildings in the Netherlands, and is maintained by Dutch municipalities. For several object types the BAG also maintains the associated geographical location and shape; for example for premises and cities. Read the complete article here. WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: Ronald van Luttikhuizen,Vennester,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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  • OpenGL ES Shader help (Blending)

    - by Chris
    Earlier I required assistance getting to grips with how to retain the alpha channel of a transparent texture in my colourised texture shader program. Whilst playing with that first version of my program (before obtaining the solution to my first requirement), I managed to enable transparency for the whole texture (effectively blending via GLSL), and I quite liked this, and I would now like to know if and how it is possible to retain this blending effect, on top of the existing output without affecting the original alpha channel - as I don't know how to input this transparency via the parameter that is already being provided with the textures alpha channel. A basic example of the blending program I am referring to (minus any other functionality) is as follows... varying vec2 texCoord; uniform sampler2D texSampler; void main() { gl_FragColor = vec4(texture2D(texSampler,texCoord).xyz,0.5); } Where 0.5 is the transparency (blending effect) of the whole texture. This is the current version of my program, which provides the ability to colour a texture according the colour parameter passed to the program, and retains the alpha channel of the original texture. varying vec2 texCoord; uniform sampler2D texSampler; uniform vec3 colour; void main() { gl_FragColor = vec4(colour,1) * vec4(texture2D(texSampler,texCoord).xyz,texture2D(texSampler,texCoord).w); } I need to know if it is possible to apply transparency on top this program, without affecting the original alpha channel which I have already preserved. I hope this makes enough sense, I am sure it is possible, and if so I should imagine it is rather simple, but this has me stumped. Any help much appreachiated. Cheers, Chris

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  • How to do the Geometry Wars gravity well effect

    - by Mykel Stone
    I'm not talking about the background grid here, I'm talking about the swirly particles going around the Gravity Wells! I've always liked the effect and decided it'd be a fun experiment to replicate it, I know GW uses Hooke's law all over the place, but I don't think the Particle-to-Well effect is done using springs, it looks like a distance-squared function. Here is a video demonstrating the effect: http://www.youtube.com/watch?v=YgJe0YI18Fg I can implement a spring or gravity effect on some particles just fine, that's easy. But I can't seem to get the effect to look similar to GWs effect. When I watch the effect in game it seems that the particles are emitted in bunches from the Well itself, they spiral outward around the center of the well, and eventually get flung outward, fall back towards the well, and repeat. How does he make the particles spiral outward when spawned? How does he keep the particle bunches together when near the Well but spread away from each other when they're flung outward? How does he keep the particles so strongly attached to the Well?

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  • Doubling the DPI with a shader?

    - by Mathias Lykkegaard Lorenzen
    I'm developing a game where the map is generated with Perlin Noise, but on the CPU. I am generating some perlin noise onto a texture with a small size, and then I stretch it out to the whole screen to simulate a map. The reason for the CPU generating the noise is that I want it to look the same on all devices. Now, here's the end-result. Please ignore the bullets and the explosion on the picture. What matters is the background (the black/gray pixels) and the ground (the brown-ish pixels). They are rendered to the same texture through perlin noise. However, this doesn't look very pretty. So I was wondering if it would be possible to double the amount of pixels using a shader, and rounding edges at the same time? In other words, improve the DPI. I'm using SharpDX with DirectX 11, through its toolkit feature. But any help that'll lead me in the right direction (for instance through HLSL) would be a great help. Thanks in advance.

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  • loading a heightmap as texture in shader

    - by wtherapy
    I have a height map of 256x256, containing, foreach cell, not only height as a normal float value ( not 0-1 ) and also 2 gradient values ( for X and Y ), also as normal float values ( not 0-1 ). I have uploaded the texture via normal texture loading: glEnable( GL_TEXTURE_2D ); glGenTextures( 1, &m_uglID ); DEBUG_OUTPUT("Err %x\n", glGetError()); glBindTexture( GL_TEXTURE_2D , m_uglID ); DEBUG_OUTPUT("Err %x\n", glGetError()); glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB32F, unW + 1, unH + 1, 0, GL_RGB, GL_FLOAT, pvBytes ); DEBUG_OUTPUT("Err %x\n", glGetError()); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_LINEAR); DEBUG_OUTPUT("Err %x\n", glGetError()); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_LINEAR); DEBUG_OUTPUT("Err %x\n", glGetError()); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); DEBUG_OUTPUT("Err %x\n", glGetError()); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); DEBUG_OUTPUT("Err %x\n", glGetError()); as a parenthesis, the debug output is: Err 500 Err 0 Err 0 Err 0 Err 500 Err 500 Err 0 Err 0 pvBytes is a 256x256 array of typedef struct _tGradientHeightCell { float v; float px; float py; } TGradientHeightCell, *LPTGradientHeightCell; then, m_ugl_HeightMapTexture = glGetUniformLocation(m_uglProgram, "TexHeightMap"); I load it via: glEnable(GL_TEXTURE_2D ); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D , pTexture->GetID()); glUniform1i(m_ugl_HeightMapTexture, 0); in shader, I just access it: uniform sampler2D TexHeightMap; vec4 GetVertCellParameters( uint i, uint j ) { return texture( TexHeightMap, vec2( i, j ) ); } vec4 vH00 = GetVertCellParameters( i, j ); My problem is that, when passing negative values in one of the values in TGradientHeightCell ( v, px, py ), the texture is corrupted. I need the values to be passed exact as I have them in memory. Any help appreciated.

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  • PCF shadow shader math causing artifacts

    - by user2971069
    For a while now I used PCSS for my shadow technique of choice until I discovered a type of percentage closer filtering. This method creates really smooth shadows and with hopes of improving performance, with only a fraction of texture samples, I tried to implement PCF into my shader. This is the relevant code: float c0, c1, c2, c3; float f = blurFactor; float2 coord = ProjectedTexCoords; if (receiverDistance - tex2D(lightSampler, coord + float2(0, 0)).x > 0.0007) c0 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(f, 0)).x > 0.0007) c1 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(0, f)).x > 0.0007) c2 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(f, f)).x > 0.0007) c3 = 1; coord = (coord % f) / f; return 1 - (c0 * (1 - coord.x) * (1 - coord.y) + c1 * coord.x * (1 - coord.y) + c2 * (1 - coord.x) * coord.y + c3 * coord.x * coord.y); This is a very basic implementation. blurFactor is initialized with 1 / LightTextureSize. So the if statements fetch the occlusion values for the four adjacent texels. I now want to weight each value based on the actual position of the texture coordinate. If it's near the bottom-right pixel, that occlusion value should be preferred. The weighting itself is done with a simple bilinear interpolation function, however this function takes a 2d vector in the range [0..1] so I have to convert my texture coordinate to get the distance from my first pixel to the second one in range [0..1]. For that I used the mod operator to get it into [0..f] range and then divided by f. This code makes sense to me, and for specific blurFactors it works, producing really smooth one pixel wide shadows, but not for all blurFactors. Initially blurFactor is (1 / LightTextureSize) to sample the 4 adjacent texels. I now want to increase the blurFactor by factor x to get a smooth interpolation across maybe 4 or so pixels. But that is when weird artifacts show up. Here is an image: Using a 1x on blurFactor produces a good result, 0.5 is as expected not so smooth. 2x however doesn't work at all. I found that only a factor of 1/2^n produces an good result, every other factor produces artifacts. I'm pretty sure the error lies here: coord = (coord % f) / f; Maybe the modulo is not calculated correctly? I have no idea how to fix that. Is it even possible for pixel that are further than 1 pixel away?

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