All Questions
14,666
questions
179
votes
7
answers
308k
views
How to compile for Windows on Linux with gcc/g++?
I have written some effects in C++ (g++) using freeglut on Linux, and I compile them with
g++ -Wall -lglut part8.cpp -o part8
So I was wondering if it is possible to have g++ make static compiled ...
- 6,463
126
votes
9
answers
83k
views
opengl: glFlush() vs. glFinish()
I'm having trouble distinguishing the practical difference between calling glFlush() and glFinish().
The docs say that glFlush() and glFinish() will push all buffered operations to OpenGL so that one ...
- 19.6k
115
votes
1
answer
240k
views
How to properly link libraries with cmake?
I can't get the additional libraries I am working with to link into my project properly.
I am using CLion, which uses cmake to build it's projects. I am trying to use several libraries in conjunction ...
- 3,603
104
votes
3
answers
135k
views
How to use glOrtho() in OpenGL?
I can't understand the usage of glOrtho. Can someone explain what it is used for?
Is it used to set the range of x y and z coordinates limit?
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
It means that ...
- 31.5k
101
votes
5
answers
80k
views
Confusion between C++ and OpenGL matrix order (row-major vs column-major)
I'm getting thoroughly confused over matrix definitions. I have a matrix class, which holds a float[16] which I assumed is row-major, based on the following observations:
float matrixA[16] = { 0, 1, 2,...
- 72.8k
89
votes
5
answers
38k
views
What is the role of glBindVertexArrays vs glBindBuffer and what is their relationship?
I'm new to OpenGL and Graphics Programming. I've been reading a textbook which has been really thorough and well-written so far.However, I've hit a point in the code that I'm not quite understanding ...
- 945
85
votes
10
answers
116k
views
Drawing Sphere in OpenGL without using gluSphere()?
Are there any tutorials out there that explain how I can draw a sphere in OpenGL without having to use gluSphere()?
Many of the 3D tutorials for OpenGL are just on cubes. I have searched but most of ...
- 15.3k
80
votes
7
answers
239k
views
How to get the GL library/headers?
#include <gl\gl.h>
#include <gl\glu.h>
#include <gl\glaux.h>
This is an example, but where to get GL headers?
- 5,559
73
votes
4
answers
153k
views
Understanding glm::lookAt()
I am following a tutorial to learn OpenGL in which they used glm::lookAt() function to build a view but I cannot understand the working of glm::lookAt() and apparently, there is no detailed ...
- 1,683
70
votes
11
answers
47k
views
How to Practically Ship GLSL Shaders with your C++ Software
During OpenGL initialization, the program is supposed to do something like:
<Get Shader Source Code>
<Create Shader>
<Attach Source Code To Shader>
<Compile Shader>
Getting ...
- 4,938
65
votes
2
answers
60k
views
Camera position in world coordinate from cv::solvePnP
I have a calibrated camera (intrinsic matrix and distortion coefficients) and I want to know the camera position knowing some 3d points and their corresponding points in the image (2d points).
I know ...
- 11.7k
61
votes
6
answers
48k
views
Why are SDL and OpenGL related?
I was messing around with SDL and found out that you cannot rotate images with SDL. Everywhere the question was asked, people said to use OpenGL to do rotation. I always thought that SDL was ...
- 2,737
57
votes
6
answers
78k
views
Calculating normals in a triangle mesh
I have drawn a triangle mesh with 10000 vertices(100x100) and it will be a grass ground. I used gldrawelements() for it. I have looked all day and still can't understand how to calculate the normals ...
- 623
57
votes
4
answers
27k
views
Segmentation fault at glGenVertexArrays( 1, &vao );
My gdb backtrace gives:
(gdb) backtrace
#0 0x00000000 in ?? ()
#1 0x0804a211 in init () at example1.cpp:147
#2 0x0804a6bc in main (argc=1, argv=0xbffff3d4) at example1.cpp:283
Not very ...
- 1,277
53
votes
5
answers
20k
views
What are some best practices for OpenGL coding (esp. w.r.t. object orientation)?
This semester, I took a course in computer graphics at my University. At the moment, we're starting to get into some of the more advanced stuff like heightmaps, averaging normals, tesselation etc.
I ...
- 4,071
53
votes
2
answers
52k
views
OpenGL bool uniform?
I'm trying to send a boolean to an OpenGL glsl shader.
Currently I have this in the shader:
uniform bool foo;
And I use this to set it:
glUniform1i(glGetUniformLocation(shader, "foo"), true);
...
- 9,817
52
votes
6
answers
158k
views
How to draw text using only OpenGL methods?
I don't have the option to use but OpenGL methods (that is glxxx() methods). I need to draw text using gl methods only. After reading the red book, I understand that it is possible only through the ...
- 529
51
votes
3
answers
66k
views
How to initialize a glm::mat4 with an array?
I'm using the OpenGL Mathematics Library (glm.g-truc.net) and want to initialize a glm::mat4 with a float-array.
float aaa[16];
glm::mat4 bbb(aaa);
This doesn't work.
I guess the solution is ...
- 5,700
49
votes
2
answers
35k
views
VBOs with std::vector
I've written a model loader in C++ an OpenGL. I've used std::vectors to store my vertex data, but now I want to pass it to glBufferData(), however the data types are wildly different. I want to know ...
- 101k
49
votes
4
answers
78k
views
Learning OpenGL in Ubuntu [closed]
I'm trying to learn OpenGL and improve my C++ skills by going through the Nehe guides, but all of the examples are for Windows and I'm currently on Linux. I don't really have any idea how to get ...
- 6,738
45
votes
1
answer
5k
views
Efficient off-screen rendering of QPainterPaths (OpenGL and non-OpenGL solution required)
In my application, I paint a street map using QPainter on a widget
made by QPainterPaths that contain precalculated paths to be drawn
the widget is currently a QWidget, not a QGLWidget, but this ...
- 45.5k
43
votes
5
answers
69k
views
How to render offscreen on OpenGL? [duplicate]
My aim is to render OpenGL scene without a window, directly into a file. The scene may be larger than my screen resolution is.
How can I do this?
I want to be able to choose the render area size to ...
- 4,104
43
votes
4
answers
72k
views
Generating a normal map from a height map?
I'm working on procedurally generating patches of dirt using randomized fractals for a video game. I've already generated a height map using the midpoint displacement algorithm and saved it to a ...
- 2,723
40
votes
2
answers
2k
views
X hangs up because of application (use C++, Qt, OpenGL)
My application gets data from the network and draws it on the scene (scene uses handmade OpenGL engine).
It works for several hours. When I'm not using my desktop, my monitor, because of Display ...
- 585
39
votes
7
answers
36k
views
How to pass an std::string to glShaderSource?
I have the following code:
glShaderSource(shader, 1, (const char **)data.c_str(), NULL);
But it makes my program crash. How do I convert std::string into const char ** ?
I also tried (const char **)...
- 3,773
39
votes
2
answers
34k
views
Develop using OpenGL 4.x on OSX Big Sur
According to Apple, OpenGL is no longer supported. However, it appears v4.1 of OpenGL was supported on many devices as of July 28, 2020. I have a 2020 Macbook Pro 16" model, which does not show ...
- 906
39
votes
6
answers
20k
views
Learning modern OpenGL
I am aware that there were similar questions in past few years, but after doing some researches I still can't decide where from and what should I learn.
I would also like to see your current, actual ...
- 1,650
38
votes
4
answers
71k
views
error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup, but this time it's NOT a Windows/Console problem!
So, the infamous error is back. The project is complaining that it can't find the main() method (that's what the error means, right).
However I do have a main, and my project is a Console project, as ...
- 1,554
37
votes
1
answer
16k
views
glVertexAttribPointer raising GL_INVALID_OPERATION
I'm trying to put together a very basic OpenGL 3.2 (core profile) application. In the following code, which is supposed to create a VBO containing the vertex positions for a triangle, the call to ...
user269597
37
votes
3
answers
25k
views
glPixelStorei(GL_UNPACK_ALIGNMENT, 1) Disadvantages?
What are the disadvantages of always using alginment of 1?
glPixelStorei(GL_UNPACK_ALIGNMENT, 1)
glPixelStorei(GL_PACK_ALIGNMENT, 1)
Will it impact performance on modern gpus?
- 50.5k
37
votes
3
answers
36k
views
What's the advantage of using GLuint instead of unsigned int?
I like to be more standard as possible, so why should I "constrain" my classes defining it's members as OpenGL types when I can use primitive types? Is there any advantage?
- 635
36
votes
1
answer
65k
views
Error1 error LNK1107: invalid or corrupt file: cannot read at 0x2B0
I am new in opengl and i have no idea what this error means. I am using Visual Studio 2012 > C++ > Empty Project.
I Follow these steps in other pc thats work for me but i am doing this in my pc ...
- 735
36
votes
3
answers
5k
views
Organizing GLSL shaders in OpenGL engine
Which is better ?
To have one shader program with a lot of uniforms specifying
lights to use, or mappings to do (e.g. I need one mesh to be parallax mapped, and another one parallax/specular mapped)....
- 3,051
35
votes
1
answer
23k
views
Point Sprites for particle system
Are point sprites the best choice to build a particle system?
Are point sprites present in the newer versions of OpenGL and drivers of the latest graphics cards? Or should I do it using vbo and glsl?
- 1,001
35
votes
2
answers
6k
views
Visualising 4D objects in OpenGL [closed]
Do you know of any, actively developed, C/C++ library that can take a bunch (preferably a large amount) of 4D vertices, project them back into 3D space with respect to some arbitrary "4D camera" ...
- 1,183
35
votes
1
answer
1k
views
Packing arbitrary triangles into a finite box?
I need to pack triangles into a box as tightly as reasonable, as part of a 3D optimization (I'm stuffing alpha-using segments of different textures into a single different texture, for use with depth-...
- 12.8k
33
votes
3
answers
28k
views
In What Order Should I Send My Vertices To OpenGL for Culling
I'm learning a spot of 3d opengl, and it's going rather well, I've got a nice camera moving about and some simple cube objects, at the moment. Currently using vertex arrays, but I'm swapping to VBOs ...
- 1,853
33
votes
5
answers
9k
views
Windowless OpenGL
I would like to have a windowless OpenGL context (on both GNU/linux with Xorg and Windows). I'm not going to render anything but only call functions like glGetString, glCompileShader and similar.
I'...
- 2,703
32
votes
2
answers
81k
views
How to use alpha transparency in OpenGL?
Here's my code:
void display(void);
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGBA);
glBlendFunc(GL_SRC_ALPHA, ...
- 4,541
32
votes
1
answer
46k
views
Is glm::ortho() actually wrong?
I recently thought it would be a good idea to switch from the old (deprecated) functionality that OpenGL provides, such as matrix operations and the fixed function pipeline.
I am using GLM as my ...
- 548
32
votes
1
answer
68k
views
Cmake link library target link error
Hi I have problem with linkg Glfw and other libraries using cmake.
From command line i compile like this
g++ main.cpp -lGL -lGLU -lGLEW -lglfw
But I wanted to use cmake for compiling. I tried to use ...
- 677
32
votes
4
answers
27k
views
Easy framework for OpenGL Shaders in C/C++
I just wanted to try out some shaders on a flat image. Turns out that writing a C program, which just takes a picture as a texture and applies, let's say a gaussian blur, as a fragment shader on it is ...
- 13.6k
32
votes
5
answers
2k
views
OpenGL, How to create a "bumpy Polygon"?
I am unsure of how to describe what I'm after, so I drew a picture to help:
My question, is it possible within OpenGL to create the illusion of those pixel looking bumps on a single polygon, without ...
- 12.8k
32
votes
3
answers
19k
views
Understanding Vertex Array Objects (glGenVertexArrays )
I am confused with the point in generating/creating a Vertex Array Object (VAO) with:
glGenVertexArrays(GLsizei n, GLuint *arrays);
and
glBindVertexArray(GLuint);
Because I can still create a ...
- 481
32
votes
1
answer
7k
views
Qt3D: How to render a mesh in wireframe mode using Qt C++?
Qt3D documentation is increasing but still lacking some information especially on how to do things without Qml/QtQuick. After heavily searching the web about rendering a mesh in wireframe mode, I ...
- 337
31
votes
2
answers
44k
views
Why does glGetString(GL_VERSION) return null / zero instead of the OpenGL version?
I'm on Linux Mint 13 XFCE. My problem is that when I run in terminal the command:
glxinfo | grep "OpenGL version"
I get the following output:
OpenGL version string: 3.3.0 NVIDIA 295.40
But when I ...
- 375
30
votes
2
answers
52k
views
Loading PNG with stb_image for OpenGL texture gives wrong colors
I am using stb_image to load a 32-bit PNG file (RGBA) and I am creating an OpenGL texture with it.
It works fine for 24-bit PNG files (with no alpha channel), but when I use a 32-bit PNG file, ...
- 4,352
30
votes
2
answers
30k
views
Why does my color go away when I enable lighting in OpenGL?
I am developing a graphics application in C++ with the OpenGL API and GLUT.
To add lighting, I made the following changes in my modelview matrix:
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
// ...
- 20.6k
30
votes
2
answers
9k
views
Do I have to use the OpenGL data types (GLint, CLchar, ...) for a cross platform game?
I have a short question. Why does OpenGL come with its own datatypes for standard types like int, unsigned int, char, and so on? And do I have to use them instead of the build in C++ datatypes?
For ...
- 33.4k
30
votes
1
answer
8k
views
Do uniform values remain in GLSL shader if unbound?
I am writing a program that uses two different shaders for different primitives. My question is: if I bind a program, send it uniform variables, then use another shader program and come back to the ...
- 671