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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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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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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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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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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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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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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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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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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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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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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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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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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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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Atmospheric scattering band/seperation artifact
I am currently experimenting with some atmospheric scattering in glsl in my OpenGL engine.
I am experiencing a strange phenomena where a strange band / separation artifact appears along the middle of ...
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GL_OUT_OF_MEMORY Error when glDispatchCompute takes longer
I built a simple Ray Tracer which takes use of OpenGL's Compute Shader and traces ".obj" Files.
The results are passed to the Host-Program via glMapBufferRange after finishing computing.
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Matrix transforming with translation/rotation/scale at center of screen
I'm trying to create a camera using matrix transforms, the gist as follows:
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What sort of implementation dependent limits for glPointSize can one expect from modern graphics cards?
As noted here, when rendering using the GL_POINTS primitive, there is an implementation dependent limit to the point size range.
I intend to use GL_POINTS for fast billboard rendering of particles, so ...
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Operations in the Rendering Pipeline
I have a few short question regarding operations happening in the rendering pipeline (OpenGL, Vulkan, I'd expect for all questions to have similar answers for these two frameworks while DirectX might ...
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Drawing a square using glDrawArrays with GL_TRIANGLES
I used a version of the following code to draw a triangle using glDrawArrays with GL_TRIANGLES, per Anton Gerdelan's very nice tutorial here:
Hello Triangle !
It draws a nice triangle.
I have modified ...
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Using imageLoad/imageStore to perform atomic add
I have a rgba16f texture that I fill with values using nvidia GL_NV_shader_atomic_fp16_vector extension, which allows to perform ...
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Packing a GL_RGB from three separate buffers?
I'm decoding an .mp4 to use as a texture on a tristrip. It's easy enough to use an unsigned byte array of RGB triplets to create this texture, but frames come out ...
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Problem sampling uniformly envmap with GGX
I have made a program that samples uniformly an environment map and computes the lighting using the GGX BRDF.
I have made a small example that reproduces the issue I'm having. You can check it out ...
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Is there different between 'if' and 'ternary operator' in GLSL?
I'm practicing GLSL on ShaderToy
...
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Different OpenGL behaviour on Windows and Ubuntu
While porting this project with slightly modified code to Linux I ran into some weird behaviour.
On Windows it runs just fine (https://youtu.be/xH6Dc6xOuow).
But on Ubuntu it shows some weird ...
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Using instanced arrays for dynamic objects
With the help of instanced arrays we can specify an array of transforms and render a number of objects with a single render call. I'm wondering if using instanced arrays make sense in situations where ...
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