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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Assimp - generate tangents and bitangents

I have started using Assmip 3.1.1 in my OpenGL application. Let's consider a simple example. Here is obj triangle model: mtllib triangle.mtl v -5.0 0.0 0.0 v 0.0 0.0 0.0 v 0.0 5.0 0.0 vn 0.0 0.0 ...
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30 views

Trackball Rotation using Quaternions

I am trying to figure out rotations using quaternions. I am using a trackball that tracks the mouse when I click. So when I click on the right and drag to the left, the cube rotates around the y ...
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1answer
56 views

Render model with meshes with materials and/or textures

I'm making a model class that is using Assimp in the background. I want my models' meshes to be able to have a material and an optional texture on top of that. Right now I'm doing it like this: for ...
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2answers
105 views
+50

Problems with rendering a SkyBox

At the moment I'm writing an Android OpenGL ES 2.0 game but now I get stuck on rendering a SkyBox. Here is my (a bit simplified) code for the SkyBox: float vertices [] = ...
3
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1answer
82 views

what is the very last element of a 4x4 transformation matrix for? [duplicate]

while its a similar value to its neighbour - Z translation (and I wont say if thats above or to the left for fear of sparking a religious war!) and it only seems to change when the Z translation value ...
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1answer
65 views

Looking for Bezier curve OpenGL open source implemention [closed]

well in short im looking for something like this as open source. https://www.youtube.com/watch?v=Cut3_A0Xm3Y i need to implement especially the Bezier curve editing in my app in open gl . any ideas ...
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1answer
48 views

Cubemap faces rotation in GS shader

I Can't get correct rotations for cubemap faces. Thats should come to geometry shader, from camera "view" matrix I want make 6 faces for my cubemap, but seems I can't get it correctly... My first ...
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2answers
70 views

Rendering objects with either normal maps, either specular maps, or with both, or with neither?

My hobby engine has a deferred renderer that supports normal maps and specular maps. Now, some objects may have normal maps, and some may have specular maps. In some cases, an object has both maps, ...
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1answer
50 views

glVertexAttribPointer stride ambiguity

As a hobbyist junior game programmer, I have done multiple small OpenGL projects just to have fun with 3D. I've tested VBOs in C++ and in Java and I found something or rather understood Java tutorials ...
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0answers
5 views

How do you add libraries to CMakeLists? [migrated]

After searching everywhere I could not find anything or anyone to help me figure out how to add GL GLEW and SDL2 Libraries to my CMakeLists.txt. I am using Ubuntu 14.04 LTS and I installed the ...
2
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1answer
64 views

How can I deal with vertex precision errors between terrain chunks?

I am using OpenGL to render the following scene, using vertex data from one of the map files of a popular MMORPG. The data is chunked and the pictured scene is made up of 256 (16x16) chunks. However ...
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2answers
40 views

How can I chain together Stencil tests from the same re-occurring routine, but keep the tests separate?

Sorry for the bad title; I don't know how else to explain this. I have a class called a Container. An instance of Container has other elements "inside" it. These elements have independent positions ...
2
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1answer
127 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 ...
3
votes
1answer
121 views

Should unbind buffers?

I'm making some tests with OpenGL ES 2 and got some questions, my current program is like that: Init ------- -> create index buffer -> fill index buffer glBufferData … -> create vertex ...
1
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2answers
56 views

Rendering order of shadowing point lights?

I'm implementing shadow mapping in my deferred rendering engine. I've got spot lights working, and now I'm working on point lights. Currently, I do it like this: // Loop through the point lights for ...
0
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0answers
39 views

Ray casting: need to find start and end vectors

So I have a 3D object and I'm trying to implement Maximum Intensity Projection on it. I already started of using a default vector to show per pixel, namely: pixelCoord[0] = uVec[0] * (i - ...
0
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1answer
38 views

Is it possible to store diffuse and normal maps in the same texture area and preserve SRGB/linear space?

Usually, one would want to upload texture data to OpenGL with GL_SRGB* for the internalformat of a texture, and GL_RGB* (or some other linear format) for normal data or specular highlight maps. We can ...
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0answers
30 views

Deforming meshes in OpenGL [closed]

I'm learning about OpenGL, specifically OpenGL-ES 2.0 on Android. The question I've posed to myself this evening is: how can I deform a mesh? I think I have some answers. So my questions for SE ...
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1answer
43 views

render with const depth value

This is a question that may have an answer that differs for vanilla desktop GL and GL ES 2.0 (and wishful thinking is that ES 3.0 would have the same answer as vanilla GL). What I'm doing is ...
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1answer
71 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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1answer
167 views

How can I render a JBox2D ParticleGroup?

I want to render a ParticleGroup from JBox2d using OpenGL. I've managed to define a particle group area, but I'm unsure how to draw the individual particles. Here's how I create the ParticleGroup: ...
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0answers
45 views

Why Reducing fragments by increasing geometry vertices turn out to be slow?

I am developing a ray-casting program by OpenGL. At first I made a large bounding box including the whole volume and render this box, which triggers the ray-casting. I'm trying to optimize this ...
8
votes
1answer
309 views

Creating a glitch effect similar to Watch Dogs

I'm currently working on a LibGDX game. When a user does something wrong, I would like all the graphics on the screen to jitter very similar to the glitch/distort effect seen in the game Watch Dogs ...
5
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2answers
533 views

2D games and modern OpenGL

Preconcepts Ok, so what I've gathered so far is this: don't use fixed pipeline (deprecated or going to be deprecated) vbos store "object models" (n vertex data, mostly) vaos describe how data is ...
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1answer
106 views

How can I load raw Bayer images using OpenGL?

I want to load a raw Bayer format image and convert it to RGB using OpenGL. So far I have played around with glTexImage2D() and loaded a Bayer image as a monochrome texture. My question is: how can I ...
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1answer
79 views

Fragment Shader output type error

StackExchange! I've been working with opengl for a bit and I'm trying to finally load the shaders instead of having them inline. I'm having a ton of issues, though. As soon as I solve one, another ...
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1answer
96 views

It possible to render a true quad (without triangles) using OpenGL?

Is it possible to render a "true" quad in OpenGL? By that I mean a square which is not made out of two triangles.
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1answer
46 views

How would I go about merging two models together in-game to create a new model? [closed]

Let's say I have two models: model 1 is hilt and model 2 is blade. How would I merge these to models together to create a sword?
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2answers
59 views

How to draw a textured 2D square using OpenGL

I am attempting to get started using OpenGL, and have learned how to open a window and draw basic shapes. However, I do not know how to texture them and have been unable to find any tutorials on how ...
2
votes
1answer
132 views

OpenGL light appears to move with camera and changes with object rotation

I have a working open gl es 2.0 3d engine (my own) that I've used in several iOS apps. I recently noticed that on a mutli-symmetrical object the lighting didn't look the same at each rotation. For ...
1
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1answer
61 views

model view projection multiplication order

I'm debugging a lighting problem where the camera position is effecting the diffused lighting component on my 3d model. In researching my problem I went back and am reading over all the how to ...
4
votes
2answers
384 views

Is there an alternative to VBOs or deprecated functions to draw many small quads?

I was thinking about how to program a user interface in a 3D game. The problem is, immediate mode (glBegin and glEnd) is deprecated for a long time but I don't think vertex buffer objects (or arrays) ...
1
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1answer
79 views

Why would OpenGL ignore GL_DEPTH_TEST setting?

I cannot figure out why some of my objects are being rendered on top of each other. I have Depth testing on. glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LEQUAL); Do I need to draw by order of what is ...
0
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1answer
74 views

How can I draw a ray from the camera in world space?

How can I construct a ray from the camera position to where it looks at, in world space. My previous method is draw a line by using two points. The first point is the camera position, and the other is ...
3
votes
2answers
68 views

How can I draw curves above a mesh surface?

I am making an animation of a deformed sphere that represents some aspects of the wave function in a hydrogen atom. I am starting with an octahedron that i push through a tessellation shader. The ...
0
votes
1answer
62 views

Rotate OpenGL quad around its center

Sorry, I searched it but couldn't figure how to apply it to my code reading the other answers to similar questions. I what to rotate a quad, my code is the following: glEnable(GL_TEXTURE_2D); ...
0
votes
1answer
78 views

Transformations and basis vectors

I've been reading this very nice tutorial on OpenGL, and I encountered a statement which I can't wrap my head around. In Chapter 6, it states: Transformation from one space to another ultimately ...
2
votes
1answer
40 views

Failing to move exponential depth term to depth shader in exponential shadow mapping

I'm playing around in my little toy project to see if I can understand how exponential shadow mapping works. To begin, I have the following two fragment shaders: Light depth texture shader ...
2
votes
2answers
114 views

Render-to-texture doesn't work on nvidia cards. OpenGL 3.3

I've implemented some postprocessing effects (DOF, HDR, Bloom) into my engine. I've tested it on AMD card which supports OpenGL 4.2. Yesterday I've made a test on NVidia card which supports only ...
1
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1answer
88 views

Setting up OpenGL on Mac OS 10.10 while keeping it cross-platform

I have experience with game programming mainly in allegro or drawing everything on native windows (No graphic libraries). Now I am interested in learning OpenGL for game development. I have found ...
4
votes
1answer
79 views

How to compute point in view space from depth?

I am trying to implement do some screen space rendering but after looking over the web I still don't find answers to some doubts. First, I need to compute the point in view space from a value in the ...
1
vote
1answer
50 views

Do I have to use vertexArray in opengl

GLuint VertexArrayID; glGenVertexArrays(1, &VertexArrayID); glBindVertexArray(VertexArrayID); As you can see from the above code, some tutorials use this before using opengl. But a tutorial that ...
4
votes
1answer
289 views

C++ OpenGL ShadowMap Issue/Artifacts

I am currently implementing basic shadow mapping in my C++ Custom Engine using GLSL 4.10. It is currently working with basic PCF anti-aliasing and very minimal reduction for unwanted artifacts. Here ...
0
votes
1answer
40 views

Is this equivalent to D3DXVec3TransformNormal?

I was porting some code from DirectX to OpenGL. I have the following code: glm::mat4 rotation(1.0f); rotation = glm::rotate(rotation, degrees, m_up); m_look *= rotation; where rotation is a mat4 ...
2
votes
0answers
44 views

Tangents face the same direction on opposite sides of mesh

I have noticed that the tangent vectors that I am calculating are not always facing the correct direction. The tangents on the left and right of the mesh both face the same direction. Here is a ...
4
votes
1answer
96 views

OpenGL: Volume Heat Distortion

I'm working on adding volume effects to an existent, open-source game engine. At the moment, the engine only supports two dimensional "thruster" bitmaps with a planar heat distortion drawn over the ...
0
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0answers
26 views

I just can't get glg2D to work, what is wrong?

I would like to use the glg2d library for my project (I'm using eclipse) but I always get an error. First I included jogl and gluegen, and gave it the native folder, and it seemed fine, no errors. I ...
4
votes
2answers
275 views

How does a general Renderer::drawRect(0, 0, 100, 100) handle VBO's?

Lots of game engines and GUI systems have a general Renderer class with functions like: renderer.drawRect(0, 0, 100, 100); renderer.drawText(204, 452, "Hello, world!"); I understand how this could ...
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0answers
62 views

OpenGL Occlusion Culling - flickering problems

I have implemented occlusion culling in my app and I think why the problem is happening but I am not sure how to solve it. My scene is divided in different chunks (voxels) and I am rendering each ...
0
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1answer
67 views

Reconstruct shader vertices in OpenGL

I'm not sure if 'reconstruct' is the correct term for this but essentially what I am trying to do is calculate vertex positions (that are already calculated via shader) on the CPU for the purpose of ...