OpenGL is a graphics standard and API which targets the desktop and workstation markets. It is designed to be easy to accelerate with dedicated computer hardware, and hence most implementations give greatly improved performance over traditional software rendering. Currently, OpenGL is used for ...

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3answers
241 views

Passing array to uniform in glsl error

Here is my attemps to pass array to uniform array: struct Vector{ float x,y,z; } float threshold[2] = { 0.5, 0.25 }; Vector *kernel = new Vector[_kernel_size]; // _kernel_size==16 // fill kernel ...
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0answers
25 views

Interpolating Skinning Weights

I am subdividing the triangles of mesh, and as you can guess, I need weight values for these new vertices. Currently I am using linear interpolation (Vnew.weight[i] = (V1.weight[i] + V2.weight[i]) * ...
1
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1answer
65 views

OpenGL poor performace with instanced drawing

I'm just started learning OpenGL and this is my first project besides tutorials. I'm trying to load a huge enginering model: The data is structured in a way that I thought I could use instancing ...
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3answers
191 views

How to implement Index Buffer Object (IBOs) with texture coordinates in OpenGL?

I was using IBOs to render meshes (for example a cube) from wave-front files (.obj), without texture coordinates or normals, in OpenGL. Following this, I attempted to implemented texturing. The mesh ...
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1answer
30 views

opengl matrix multiplication

Can someone provide some type of example of multiplying a 4x4 matrix without using loops? typedef struct matrix4 { data[16]; } m4; can someone provide a sample of how you you'd multiply two of ...
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0answers
15 views

OpenGL- Render to texture- a specific area of screen

I implemented FBO on my OpenGL Game. and Im rendering what is rendered to screen to a texture, the problem is that rendering to texture starts from lower left corner. look: what is rendered to ...
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2answers
47 views

How to find the “up” direction of the view matrix, with GLM

Using OpenGL and the GLM matrix library, I want to translate my camera relative to the world coordinate system. This requires me to compute the necessary view matrix. To initialise the view matrix, I ...
0
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1answer
122 views

Invalid coordinates returned by glutMouseFunc()

I am using GLUT's glutMouseFunc() function to retrieve the coordinates of mouse clicks. I want to move the object on that coordinate to another coordinate. But when I click on the object the ...
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1answer
16 views

glm Z coordinates are flipped

I am trying to render a 3D model using OpenGL. And for the projection and transformation matrices, I am using glm. I've got my model on the screen and it works just like I intended it to; except one ...
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1answer
37 views

OpenGL Shaders Ignored

I have been following this tutorial to try and start learning OpenGL. However, upon compiling my code, my triangle turns out to be black. At first I thought that there was something wrong with the ...
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0answers
29 views

OpenGL c++ terrain generation [on hold]

Im trying to use a grid of vertices ,a blendMap and a heightMap to generate a terain.And i got an error which i simply dont understand. Model.h struct coordinate{ float x,y,z; }; struct face{ ...
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1answer
614 views

How do I build Assimp with MinGW?

How can I build Assimp with cMake and MinGW? I tried, but I don't get a functioning library... Details of my attempt: I am trying to build the Open Asset Import Library (Assimp) but I have been ...
1
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1answer
621 views

Geometry shader and triangle adjacency

I'm currently trying to change my project to use GL_TRIANGLE_ADJACENCY instead of GL_TRIANGLES. Following this question, I have managed to construct my index buffer fine, but when it comes to the ...
0
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1answer
17 views

Rotating the view around the origin of the world coordinate system

In OpenGL (using shaders), I want to implement a system that will take the user's mouse as input, and then rotate the view about the origin of the rendered scene. So, I need to compute the view matrix ...
0
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0answers
16 views

Opengl Create FBO- fatal signal 11 error

in my android game, i want to render My scene in the FBO and a texture attached to it, and use that texture later, But When i use glGenFramebuffers i get this error: 07-30 06:17:27.839: A/libc(1338): ...
0
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1answer
298 views

How to compute matrix transform local/world on OpenGL

I'm developing an OpenGL program where each object / entity contains m_WorldPosition, m_WorldOrientation, m_WorldScale and m_WorldTransform (Vector3, Quaternion, Vector3 and Matrix4f). The problem is ...
1
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1answer
27 views

What are the units when reading depth using glReadPixels()?

Suppose I use glReadPixels() to read the depth of a pixel from the depth buffer. What are the units of this? Is it the distance from the camera? Or the distance from the near clip plane? And is the ...
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0answers
26 views

Fixing memory leak in Opengl texture class [on hold]

I recently run my 3D game engine under Valgrin and discovered that everything's almost fine, except that I leak 7,862 bytes in my opengl texture class... I think that I'm not calling a specific opengl ...
0
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1answer
88 views

Collision between a sphere and a mesh(height-map)

I am trying to implement a method that detects the collision between a sphere and a mesh and reflects the vector of speed. I have a method, that detects a collision between a sphere and a triangle and ...
1
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2answers
253 views

Tiled Rendering - Projection matrix

I'm trying to figure out how to perform tiled rendering of my 3d scene (OpenGL). The motivation is to cut the scene up into several textures, combining them into a single image for saving at a very ...
0
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1answer
9 views

Passing data into a vertex shader for perspective divide

In OpenGL and GLSL, I am just learning about perspective projection and the vertex shader. However, I am a little confused about what data actually needs to be passed to the vertex shader, and what ...
0
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0answers
15 views

Perspective divide: Why use the w component? [duplicate]

In OpenGL, I have read that a vertex should be represented by (x,y,z,w), where w = z. This is to enable perspective divide, whereby (x,y,z) are divided by w in order to determine their screen position ...
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0answers
15 views

GLFW - Event Polling System

I need some help on design. I'm making an event polling system, where a window is notified of events as they happen. I handle events at a system level in my GLFW backend, by using callbacks. ...
3
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1answer
154 views

FBX Importer - Vertex Color

I imported vertex positions, indices and normals successfully in OpenGL using fbx sdk, but I just can't figure out how to import vertex colors. I tried to fetch the pointer to array of colors trough ...
28
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5answers
15k views

why would you use textures that are not a power of 2?

In the early days of OpenGL and DirectX, it was required that textures were powers of two. This meant that interpolation of float values could be done very quickly using shifting and such. Since ...
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2answers
26 views

Render specific part of a texture in OpenGL (2D Sprite Sheet)

I've looked at this answer to find out how to render just a part of a texture: http://stackoverflow.com/questions/6884285/c-opengl-render-part-of-an-image I tried that, but the problem is, this is how ...
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1answer
27 views

OpenGL Core profile - Array of arrays in glBufferData for VBOs

I want to send each face as VBO, and I structured the data as this facevbo[0] = x x x x x x //x,y,z,r,g,b,s,t facevbo[1] = x x x x x facevbo[2] = x x x x x x x facevbo[3] = x x x x . . . ...
8
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1answer
231 views

Tone mapping and eye adaptation - pale colors and darker image

I'm trying to implement tone mapping along with eye adaptation and HDR. Actually I implemented this already but I'm not satisfied with result and I think that I made something wrong. My final image ...
2
votes
1answer
31 views

OpenGL ES God Ray Precision error

I have encountered the following (i think) precision error. (missing link need 10 rep) My source of inspiration was: (missing link need 10 rep) On the PC everything works fine, but on android it ...
0
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1answer
190 views

Trying to implement Camera

I'm trying to implement a Camera class in order to walk and look on the world as follow: #ifndef _CAMERA_H_ #define _CAMERA_H_ #include <glm\glm.hpp> class Camera { public: Camera(); ...
-1
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0answers
31 views

Raytracing in OpenGL

I've been looking through some raytracing information recently and I have a question. I think the only way to do raytracing in OpenGL is to use the compute shader, right ? But does it have the luck of ...
0
votes
0answers
30 views

Image speeds up while moving and or rotating instead of constant speed

I'm having a problem with rotating/moving an image. I've set one of my images to rotate on it's z-axis buy updating the angle, but when I run my game, the image starts slowly starts to rotate from a ...
0
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0answers
13 views

OpenGL, glDrawElementsInstanced behaving differently on NVIDIA GPU than AMD

I have an AMD GPU on my desktop, AMD HD 5770. I am working on a project on my desktop for over a year. In the scene, I have instanced grass and instanced trees. Everything is working fine on desktop, ...
0
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1answer
87 views

Small text is very light / faint with FreeType and OpenGL

I'm able to render large text with FreeType just fine: But when I want to render small text (and the only parameter that changes is the font size), the quality is much poorer: As you can see, ...
1
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1answer
34 views

Nvidia Nsight 4.6 VS Edition. The Graphics debugger can't find glew32.dll

I'm trying to debug some textures and FBO's with Nvidia Nsight 4.6 VS Edition. But when I select either "Start CUDA debugging" or "Start graphics debugging" I get an error. "The program can't start ...
0
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1answer
80 views

Java OpenGL Perspective matrix not working

I'm trying to render a simple triangle with OpenGL in Java using LWJGL3. Everything is working great, but the projection matrix (perspective) is not working. In C++ I just used to apply the ...
0
votes
1answer
26 views

glGenArrays - This functionality is not available

Whenever I call glGenVertexArrays(), I get the following exception: Exception in thread "main" java.lang.IllegalStateException: This functionality is not available. at ...
0
votes
1answer
103 views

How to Load a Level for use with the Bullet Physics Library

I am trying to use a level in .obj format loaded with Assimp to generate a btBvhTriangleMeshShape to use with the Bullet physics library. I can successfully load btConvexHullShapes as well ...
0
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1answer
84 views

How to clip or mask entity in adnroid/andengine?

I want to implement masking with sprite in Andengine. I want same functionality as in ios class called SKCropNode which works like an masking node! Is there any workaround like this in ...
0
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0answers
31 views

Open GL 3.3 quad not drawing

Right Now I'm just trying to draw a quad(Latter will draw a texture on it) but for some reason its not showing up. My clear color is working so openGL is working. I don't want to focus on any shaders ...
0
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0answers
28 views

Modern OpenGL Sprite Drawing - Not Rendering

I'm trying to render sprites based of this tutorial, in LWJGL. Here's what I have so far, with descriptions of what class I use: Transformable2D is a class that holds transform matrices meant for ...
0
votes
0answers
14 views

OpenGL 3.3 is not clearing color

When I open the window its show nothing with a white background. I tried earlier to draw a triangle and nothing shoed up. I belive for some reason OpenGL is just not displaying. Maybe I need to ...
0
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0answers
19 views

OpenGL, Multithreaded loading/streaming of data

I've thought about how i could implement loading of data in a second thread for two reasons, first, so i can show a nice loading-screen with progressbar and second, for openworld streaming. I came up ...
1
vote
1answer
43 views

Instanced rendering with ARB_vertex_attrib_binding

I'm trying to separate the vertex format specification from the vertex data. I was able to do that for the mesh vertices successfully. For instanced rendering I wanted to further separate the instance ...
0
votes
2answers
1k views

OpenGL : Suggestion on handling collision detection and vertex data?

I was thinking how to do collision detection in my OpenGL application and came to conclusion that I should keep two copies of my geometry data. 1)First copy : Only for OpenGL rendering purposes.This ...
1
vote
1answer
184 views

SDL & OpenGL - Artifacts when multisampling

Im trying to render a model with anialiasing using OpenGL and SDL, but when I do I get strange artifacts. When I render with antialiasing disabled everything looks fine. When antialiasing is ...
2
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0answers
51 views

OpenGL picking performance: ray casting vs. color picking

I am curious of how the performance of color picking compares to ray casting. I am looking at the scenario when the mouse is clicked which means only then the scene is rendered in a backbuffer for ...
0
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1answer
64 views

What's better - drawing every interval that the window updates, or drawing when necessary and updating when drawing?

So what's better? In case the title is a bit confusing I mean: 1) Drawing every window update interval. For example, for a 60FPS window, every 17 milliseconds. For example: ...
0
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2answers
78 views

Fragment shader compiling in webGL but not in OpenGL

I am programming in Haxe (language compiling to multiple platforms) and I have written some shaders. My fragment shader runs fine in html5, but when I try to compile for native (OS X and/or Neko, a ...
3
votes
1answer
332 views

Using textureGrad for anisotropic integration approximation

I'm trying to develop a real time rendering method using real time acquired envmap (cubemap) for lightning. This implies that my envmap can change as often as every frame and I therefore cannot use ...