Questions tagged [opengl]

OpenGL (Open Graphics Library) is a graphics standard and API which is platform-independent and available for desktop, workstation and mobile devices. It is designed to provide hardware-accelerated rendering, and hence gives greatly improved performance over traditional software rendering. OpenGL is used for applications like CAD software and computer games. The OpenGL standard, as well as OpenGL ES, is controlled by the Khronos group.

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Techniques to implement a glow that encompasses a volume

I have an old renderer from years ago written with OpenGL immediate mode. I've decided to learn Vulkan and I'm converting my old project as a way to learn the new concepts. One of the things my old ...
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How can I replicate render environment like the picture? [closed]

The parameters I have: ...
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How widespread are T-vertex artifacts nowadays?

As far as I know, OpenGL specifies that you cannot rely on precise rounding of vertex and edge coordinates for rasterization - which means that T-vertices may cause small artifacts: a continuous and a ...
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Simulate projection matrix deformation in two camera setup

For educational purposes I'm trying to simulate what a scene would look like with a perspective matrix deformation (before everything is brought to NDC) but I'm unsure how to do this. I'd like to do ...
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Problem when performing IFFT for Tessendorf's ocean waves

I am implementing Jerry Tessendorf's ocean waves as described in his paper in c++ and OpenGL. I implemented two compute shaders, one for the h_tilde_0 and its conjugate, and one for the frequency ...
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Reducing Cascaded Shadow Mapping Artifacts

I've been trying to get my cascaded shadow maps looking right for a while. I managed to fix the shimmering and most of the quantization artifacts, but for some reason the shadows still look really ...
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1answer
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Why are degenerate triangles rasterized when using GL_LINE polygon mode

I have made use of degenerate triangles when rendering a mesh. While the degenerate triangles are not rasterized when using GL_FILL polygon mode, they are when I do ...
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Calculating the intersection of two volumes

What is an efficient way to calculate the volume of intersection of two arbitrary volumes described as closed surfaces? That is, with two meshes, A and B, how do I calculate the intersection of A and ...
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how to change the near clipping plane of a perspective projection matrix for OpenGL

I am trying to only change the near clipping plane of a given perspective projection matrix for OpenGL. My problem is, that the near clipping plane is way too close, and the far clipping plane is very ...
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OpenGL Per-Object Outlining issues

I'm trying to draw onlines around the objects, the outlines for any object should be see though very other object, I've successfully been able to draw the outline but the pixels get discarded in the ...
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DirectX FVF(Flexible Vertex Format ) equivalent in OpenGL/Vulkan?

Is there any directX FVF(Flexible Vertex Format ) equivalent in OpenGL/Vulkan.
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List all faces of a mesh visible from the view of the camera Opengl

as the question suggests I have to identify all the faces that are visible from the camera's view and do some processing with them. I have a single mesh. I am thinking of giving individual faces a ...
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118 views

glBlitFramebuffer does not copy all textures

The setup I have a working bloom shader implemented which creates a fbo with two textures attached to it. The first texture holds the entire scene The other only displays objects which are supposed ...
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How does a Vertex Buffer manage memory?

I'm learning OpenGL and I'm trying to understand things properly. If my understanding is incorrect at any point, please correct me. Introduction So let's say we have a triangle. This triangle has its ...
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Why do Nvidia and AMD have to update their drivers for game releases?

I like to know the technical aspects of it. Game developers use APIs like OpenGL or DirectX. The functions provided by these APIs, I would assume, work flawlessly with all graphic cards because they ...
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How to use trackball for rotating an camera matrix in eye frame

I have a QOpenGLWidget where I use camera transformation matrix(4,4), FOV and vectors Position(4), Up(4), Forward(4). I also have an ArcBall which I can use. I managed to implement zoom and pan by ...
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Constructing relatively big point clouds from two images

I apologize in advance for this question asking for a recommendation, but I'm not so advanced in CG to research this topic myself. Basic problem I'm looking for a most suitable approach to render a ...
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OPENGL NURBS in VBA

I'm coding OPENGL with Excel VBA I'm using arkham46 package which is really great: Découvrez la 3D OpenGL 1.1 en VB6/VBA | arkham46.developpez.com I'm not able to display NURBS surfaces, only NURBS ...
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rendering a triangle has no color

I wrote a program to render a simple triangle with colors, the triangle is there but there's no color. ...
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How can I bind my texture in the correct orientation?

I have successfully completed a working program that draw a rotating sphere with a map of the world as the texture, simulating the earth in space. However, the texture is bound on it's side, i.e. all ...
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How to calculate vertex normals on a mesh with non-planar polygons

If I have a mesh consisting of polygons that are not necessarily triangles and not necessarily planar. As answered in the previous question I asked, there's no correct answer to calculating normals ...
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1answer
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OpenGL blending with the screen

I don't understand how OpenGL performs the blending of a texture on the screen. By default, the clear color is set to (0, 0, 0, 0). If we use the default blending equation GL_SRC_ALPHA and ...
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1answer
622 views

Performance difference in OpenGL compute shader vs Vulkan Compute Shader vs Cuda/OpenCL and others

I have been told there is no performance difference if you are skilled enough when it comes to gpu computing. And cuda only performs better because nvidia wants it to. I have also read graphic api's ...
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Is there an efficient way to achieve color blending in compute shaders?

What I want is a function like imageStore, but instead of replacing a value - applying a blend operation to it, e.g. addition. It is not possible to do something ...
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My OpenGL program is not drawing filled polygons

I'm trying to learn OpenGL in c++ (I used it in Java) but I have a problem, I make a triangle, but it doesn't draw on GL_FILL and in GL_LINE it just draw a line, I can't find my mistake, I guess my ...
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Does Vulkan have the equivalent of OpenGL's separable shader program and pipeline?

If you have a shader pipeline in OpenGL that goes something like the following: ...
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Understanding fragment shader coordinate system

I'm trying to create an infinitely panable grid using fragment shaders (C++/OpenGL/GLSL), and I'm having a bit of difficulty understanding the coordinate system. This is my fragment shader code, ...
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1answer
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Understanding inequality to equality in the Hartmann & Gribbs frustum planes extraction method

I've been reading this article on how to extract the plane equations from the view and projection matrices. And I can understand most of it. However, the only thing that is unclear to me (and that ...
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1answer
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Opengl : GLSL utility files

We can create header files in C/C++ which we can include in our project using #include directive but when I use this keyword in my shader it gives the error reserved keyword. If let's say I create an ...
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How can I render a triangle mesh at 10bit (or 12bit or 16bit) channel depth color?

For a vision research experiment, I have a monitor that supports 10bit/channel (=30bit color). I want to render a triangle mesh in a simple scene that uses the full bit depth, and I want to save this ...
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fastest way to “read only” from buffer

First of all I have a struct which looks like the following: ...
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How to implement PCSS correctly?

I'm trying to implement PCSS in OpenGL/GLSL, but I have problems understanding the details especially the conversions between the coordinate spaces. The existing implementations are so different from ...
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GLSL Compute Shader Setting “shared” memory buffer size

Is it possible to set the size of the shared memory of a compute shader workgroup from the host code? There is a way to do this in CUDA and I am suspecting that, since there is an GLSL extension to ...
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Is OpenGL to Metal translation layer plausible?

I am not sure if I understood it correctly, but OpenGL is high-level like Java and Metal is low-level like Assembly, aren't they? Apple seems to have abandoned OpenGL in favour of Metal, but there ...
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imageLoad() behavior for non-existent texel

Is there a way to influence the behavior of imageLoad() for accessing an image2D or uimage2D ...
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Using multiple textures in a shader

Background: I am extracting the textures for a model with Assimp and sampling those textures in the fragment shader. I have multiple uniform sampler2D textureN ...
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1answer
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OpenGL layered rendering with multiple additional clip planes per view

I want to render a scene from multiple positions and orientations. I think the geometry shader is a good choice to not use the Vertex and tessellation shaders for each camera position again. So I want ...
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OpenGL batch drawing debug meshes with varying dimensions

When having a high number of identical meshes one could use instanced arrays to avoid gpu call overhead. For instance if we want to draw lots of cubes with the same dimensions with different ...
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1answer
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Problem using Decaling with Stencil to avoid Z-fighting

I need to create a decaling into a surface like a mesh, and to avoid Z-fighting I've been using Stencil Buffer to Turn-off depth test and make the decaling over the surface the Stencil Op permits. In ...
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is focal length equal to the distance from the optical center to the near clipping plane- openGL

The part confusing about opengl during studying the projection was that the focal length, top, left, bottom, right, wasn't declared, and it magically did it with FOV and image aspect ration. I ...
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algorithm that openGL uses to construct 3D surface from vertices

a 3D model is a collection of points, and basically a 3D software has algorithm to find out how those points connect to make surfaces. I'm searching for what those algorithms are called, that can use ...
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Comparing different sampling methods for GGX IBL

I have made a demo that shades a sphere with an environment map. I wanted to compare 3 different ways of sampling the environment. Uniform sampling. Importance sampling with the NDF as suggested in ...
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OpenGL: “invalid value” error after call to `glGetBufferSubData`

My first question in this community. I have following code.The code is shortened for clarity, error checks skipped: ...
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Efficiently transferring only needed parts of the vertex data to the GPU (C++/OpenGL)

I have a situation, where I have an array of vertices on the CPU side, for which, besides rendering-relevant data, like their position, I have a lot of other data at each vertex. All vertex data is ...
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1answer
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OpenGL Polygon Offset Fill implementation example code

I am working on a pure java implementation of OpenGL 1 called jGL. I am missing glPolygonOffsetFill and am looking for an example implementation in java, c/c++ example of this GL function in order to ...
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1answer
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PNG textures render correctly in Blender, but not in OpenGL program

I've been following the OpenGL tutorials from ThinMatrix and I've been able to load and render his stall.obj model along with his stall.png texture just fine. But when I try with my own models and ...
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Render fragments with uvs outside (0,1) range as transparent

I'm rendering an image onto a mesh. And I need to render fragments with uv coordinates that fall outside (0,1) range with full transparency. In the code below I'm specifying a border color with zero ...
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1answer
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Equally distribution on triangle surfaces

I would like to implement a random placement for objects like trees stones etc. on a triangles surface. The important part is to have an equally probability to place an object on this surface. That ...
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Possible approach to drawing with a texture brush

I would like to draw onto a plane with a 2d texture when pressing down the mouse. Similar to drawing on a canvas with a texture brush with continuous stroke in painting applications. I was thinking ...

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