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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16 views

Should I use fixed function pipeline until I can get a newer OpenGL book? [on hold]

I am planning on making a game and I have gotten as far as creating a voxel terrain generator just from watching tutorials of YouTube but decided I didn't completely understand how it worked and so I ...
1
vote
1answer
63 views

Can you trilinear sample a non volume texture?

Let's say that i have a regular 2d texture (not a volume texture). Is it possible to do trilinear texture sampling of that texture even though it isn't a volume texture in opengl or directx? ...
3
votes
2answers
2k views

FBX Importer - Texture Name

I have a problem with the FBX SDK. I read in the data for the vertex position and the uv coordinates. It works fine, but now I want to read for each polygon to which texture it belongs, so that I can ...
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0answers
18 views

OpenGL HUD is flickering when rotating the camera

I draw game HUD after drawing 3D scene. When I move the camera quickly, HUD starts flickering. I noticed that it happens only if the distance between the camera and an object its looking at changes ...
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1answer
173 views

Android OpenGL and non premultiplied textures

As I understand it; by default all bitmaps will will get the alpha channel premultiplied in Android if loaded using BitmapFactory. My setup: I have a 32bit bitmap(.bmp) where the alpha channel has a ...
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0answers
18 views

OpenGL Quad Tessellation - What kind of VBO?

I'm just getting into tessellation and after drawing and tessellating a triangle, I want to try a quad. If I change the TCS to output 4 vertices, the TES to expect a quad and the patch size to 4, only ...
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1answer
91 views

Encoding Float to RG/RGBA and Blending

Encoding a float value inside a RG or RGBA texture is very interesting and useful but it is also become quite useless when you use blending as the result and the values might be altered because of ...
3
votes
1answer
201 views

Pyglet: text.Label().draw to FBO?

I just started OpenGL (PyopenGl) & Pyglet 3 weeks ago, and decided to read the Red Book. So sorry if my question shows my lack of comprehension... My question is: Is it possible to display/write ...
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1answer
84 views

How to make TMXTiledMap responsive?

I've been struggling with Cocos2d-x (C++) and finally I got to the point I feel more or less comfortable with that. My game is a 2D car-based one, with a straight infinite map where I've finally been ...
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2answers
122 views

Z-Value of clip-space position is always 1.0

I render a lot of quads on the screen into z direction (20 x 2000). I want to get the depth value in a final render target. But it looks like z is always 1.0f. I checked the result with the OpenGL ...
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0answers
30 views

OpenGL weird pixels

I'm creating a simple OpenGL application. I've created a tilemap where I put tiles to be rendered (just a simple grid). If I only render the walls, it's ok. If I only render the ground it's ok too. ...
2
votes
1answer
122 views

Drawing fonts with LWJGL3 with OpenGL

I'm very sorry if this question has already been answered, but since I've been struggling with this for many days I thought I'd give it a shot here. My goal is to somehow render some text on the ...
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3answers
259 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
37 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]) * ...
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vote
1answer
70 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
199 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
39 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
21 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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vote
2answers
51 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 ...
0
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1answer
17 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 ...
0
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1answer
38 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
35 views

OpenGL c++ terrain generation [closed]

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
622 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
vote
1answer
624 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
votes
1answer
20 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 ...
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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): ...
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votes
1answer
300 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
vote
1answer
28 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 ...
0
votes
0answers
27 views

Fixing memory leak in Opengl texture class [closed]

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
votes
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
vote
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
votes
1answer
10 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 ...
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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
17 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
votes
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
votes
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 ...
0
votes
2answers
28 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 ...
0
votes
1answer
28 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
votes
1answer
236 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
32 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
votes
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
votes
0answers
33 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
31 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
votes
0answers
14 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
votes
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
vote
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
votes
1answer
82 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
30 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
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1answer
106 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 ...