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Questions tagged [opengl]

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 applications like CAD software and computer games. It is also cross-platform. The OpenGL standard is controlled by the Khronos group, which also controls OpenGL ES.

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Is Frustum Culling and Occlusion Culling used together, or separately?

I am taking a 3D game programming course and my professor provided the class with already-implemented graphics code with OpenGL. The graphics uses frustum culling to remove primitives outside the view ...
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7answers
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Why does the resolution of floating point numbers decrease further from an origin?

My OpenGL scene has objects that are positioned at ridiculously far distances away from the origin. When I view these objects, and pan/rotate/zoom a camera around them, they 'jitter'. That is, the ...
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32 views

About uniform block alignment

I am working on a project need programming in GLSL, and new to this. I need create a uniform block holding members of scarlars, vectors, matrices and structures. I read the guideline of uniform block ...
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1answer
34 views

OpenGL Tiled map texturing problem

Some Tiles in my map are drawn wrong, I think it might be a indexing problem. Here's the output : some tiles just look wrong!! I'm not sure where i'm going wrong with my code, so please take a look. ...
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1answer
1k views

Input in OpenTK

How to use Input in OpenTK 1.0? There is not much info around, some classes are unfinished. What I want to achieve, is to be able to use input not only in OnUpdate function, but also in other classes ...
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rayTest for cutted by stencil objects

I have red rectangle based on which I am cutting (using opengl stencil) all of the green rectangles, like shown in the following screenshots a) before cut b) after cut When I run rayTest(bullet ...
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2answers
23 views

cutting part of object

How to cut part of the object if it is inside a specific area? like showed on attached image. PS Looks like stencil should be used, but I am not really sure how to do it.
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5answers
31k views

What is the purpose of glScissor?

I know that it is more efficient than stencil test, but am I right assuming that the same functionality could be achieved using projection transformations with viewport?
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12answers
2k views

3D theory before graphics APIs? [closed]

I'm a software engineer and I'm hoping to move my career towards game development. I'm reading a book right now on 2D using C++/DirectX. When I get into 3D I know I want to do it correctly. For ...
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2answers
331 views

clamp a 2D coordinate to fit within an ellipse

I need to clamp a 2D coordinate to fit within an ellipse. Call of Duty: Modern Warfare 2 does something similar where capture points are translated from a 3D vector in the world to a 2D screen ...
4
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1answer
750 views

How to achieve cavalier projection using OpenGL fixed pipeline?

I want to make a quick demo program showing a cube, or a user loaded model, rotating in screen rendered with one of three projections: perspective, isometric and cavalier. Using the fixed pipeline, ...
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1answer
2k views

What's wrong my code to create a GL texture from an SDL_Surface?

I have an issue here with converting an existing SDL_Surface into an OpenGL texture. The texture gets created, but it's a plain white texture, below is a screenshot of the result: It seems to me ...
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1answer
16 views

What's the best practice to use the pbo to upload multi textures?

I have a basic model to upload textures as shown in the following picture. I design this for several reasons: Only the primary thread owns the OpenGL context, so I choose to create buffers, map ...
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2answers
4k 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 ...
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1answer
2k views

When do I need to call `glUseProgram`?

Looking at examples at http://learnopengl.com/#!Getting-started/Hello-Triangle and many different places, I've found that the draw sequence usually goes like this: ...
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0answers
14 views

TBN matrix for normal and parallax mapping

I'd like to refer to this question because I didn't completely answer to my problem. I've implemented normal and parallax mapping but because of some assumptions I have to use two different TBN ...
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2answers
114 views

“RuntimeError: Validation failure (0)” using shaders

I'm trying to move away from using glVertex() in my game code because it doesn't seem to work well with a large quantity of vertices. At the moment I'm trying to make code that uses Shaders, but when ...
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1answer
37 views
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1answer
44 views

Animate some tiles of tile map

I have a game where each "tile" of the terrain is a triangle (Settlers 2). Those are placed next to each other and in way creating an infinite world (right/bottom jumps back to left/top). There is a ...
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1answer
19 views

Order of rotation in Euler angles

I'm want to control the direction my camera looks, so I'm using Euler angles, so rotating around an axis is relative to rotation around previous axis. Something like this. I want to always rotate ...
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1answer
18 views

Detect collision with bullet physics, to make a character controller

I inherited from btCollisionWorld::ContactResultCallback but I really have no idea how to use this virtual function: ...
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3answers
573 views

How to hide a post-processed mesh outline when/where the mesh is hidden

I'm working on setting up an active outline in my 3d engine, a highlight effect for selected 3d characters or scenery in the screen. After working with the stencil buffer and getting some ...
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1answer
40 views

Problem with rotation a camera with the mouse OPENGL GLFW

I am trying to move my camera with my mouse, I can translate it juste by changing the current position of my camera, but when I want to move my forward vector and my up vector of my camera it doesnt ...
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1answer
187 views

Show only some parts of a point cloud. OpenGl4

I am developing an opengl 4.0 app which is showing a point cloud. In the other hand, I have an array "pos" where I have some x,y,z positions: ...
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1answer
444 views

LibGDX - Draw multiple textures with different positions with one shader?

currently I'm optimizing my render calls by drawing multiple textures with one shader. The background textures who all share the same position are no problem. But now I want to draw some Textures with ...
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2answers
41k views

Where to start learning OpenGL with C++? [duplicate]

Possible Duplicate: What are some good learning resources for OpenGL? I have learnt C++ and made some cool text based games and such but I would love to start graphical programming. I'm a decent ...
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1answer
79 views

How can I access an OpenGl buffer from within a GLSL 330 shader?

I am currently attempting to create a simulation using OpenGl's GPU acceleration for both the simulation computations and rendering. The rendering portion of my simulation is complete and working, but ...
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1answer
390 views

Specular Light not working (Phong Lighting)

There seems to be a problem with my current Phong Shading implementation. I have been using the per fragment approach. The specular highlight aspect of the technique is not rendering as it should, as ...
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1answer
105 views

opengl bump mapping (normal mapping) problem with VBO and GLSL

hi i am beginner i am trying to implement bump mapping with vbo and glsl. My question is: did i make bump mapping ? if i did why these edges didnt disappear ? high and low meshes (i used low meshes ...
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1answer
71 views

Should I throw out game heavily using OpenGL 2.0 and rewrite it from scratch?

I've picked up one old open source game (done with C++/Lua) with a lot of features and chosen to continue its development. It use SDL2 (ported by me from 1.2) and OpenGL 2.0. Now when I look at futher ...
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1answer
117 views

OpenGL Parallax Displacement Mapping Not Working

I am attempting to implement parallax displacement mapping into my OpenGL code but it is not working as it should. https://imgur.com/a/9yIQL As I move around, double-lines moves around and if I am ...
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3answers
188 views
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0answers
24 views

OpenGL texture management

I have an OpenGL engine built using bindless textures, which allows me to store all materials in an UBO and drawing thousands of instances with different materials in one pass, by accessing the ...
4
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1answer
2k 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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2answers
50 views

Getting Model View Matrix by hand

Right now I'm trying to calculate the model view MAtrix by hand... The App is 2D. I have Somethign like this.. ...
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1answer
140 views

Offset on camera following object that accelerates

I have camera a that is actively following an object (a plane) from behind. This object can accelerate or decelerate. I would like to have a camera offset when I move the plane, so it doesn't look so ...
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1answer
503 views

Render Stutter - OpenGL or loop timing?

For some time now i have no been able to pinpoint the nature of the rendering stutter shown above(by not clearing the screen, not using SwapBuffers and drawing only to the front buffer). See the big ...
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0answers
23 views

btRigidBody world transform and scale issue

When I create a collision shape for rigid body (in this case box) I use vertices positions and scale from the opengl matrix, the code looks this way: ...
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1answer
437 views

Why is my model rotating opposite direction around the Y axis?

I have a simple scenario. I have a simple scene, and in it I'm drawing a grid and a model, with some axis for orientation. I noticed when I rotate the model about it's local Y axis, if I rotate the ...
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3answers
292 views

Where did I lose vertex binding?

I make OpenGL render framework for my bachelor graduate work. I created simple Model and Shader classes. But when I tried to render some vertices, they do not render. I saw with an OpenGL profiler, ...
3
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1answer
731 views

Minecraft Modding - How do I use OpenGL stencil functions alongside the game's GlStateManager?

Note: I am using Minecraft Coder Pack 9.10 for game version 1.8.0 (official release). I am trying to make a multiline text field similar to the game's original net.minecraft.client.gui.GuiTextField. ...
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2answers
156 views

How can I represent a 2d UI?

So, I wanted to start building a desktop application, which is of course with an interface, and I thought that OpenGL would be best. The problem is, once I started following TheChernoProject's ...
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1answer
31 views

How to change object details based on zoom

I have created the map of a huge terrain (10,000 x 12,000) vertices, which results in about 240 million triangles. Loading all these is very heavy and slows down the scene significantly. To make it ...
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2answers
29k views

How many textures can usually I bind at once?

I'm developing a game engine, and it's only going to work on modern (Shader model 4+) hardware. I figure that, by the time I'm done with it, that won't be such an unreasonable requirement. My ...
3
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1answer
249 views

How to generate a multiplier map for radiosity

I am following this tutorial: here I am at the part where you are creating a hemicube. I have got the code to render the scene into a texture and therfore an array. Now how can I generate a so-called ...
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1answer
54 views

Frame Buffer Object (FBO) is not working. What is the right way to use?

I am trying to use FBO but i am living some problems. I will show you my steps but first i will show my running screen ,so we can compare them. Like before fbo after fbo. My running screen and Draw() ...
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1answer
50 views

Adjusting view matrix when glViewPort & resizing

I have an issue when my window resizes. I have a simple MVP shader like this gl_Position = projection * view * model * vec4(in_Position, 1.0); to render a map ...
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1answer
38 views

Wrong angles given by atan2

I have a method to calculate angle between two vectors, but it is giving wrong values. here is the code : ...
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1answer
56 views

How OpenGL running without GPU?

Every tutorial on OpenGL mentions that, OpenGL codes are commands executed by the GPU. Few days ago, my GPU cashed and I removed it from my computer. But the same OpenGL programs are still ...
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0answers
21 views

OpenGL outline of clip plane

I've implemented a clipping and capping view similar to the example called "simplecap.zip" in this page: http://users.polytech.unice.fr/~buffa/cours/synthese_image/DOCS/trant.sgi.com/opengl/examples/...