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OPENGL QUESTIONS

GLSL array of struct members locations
GLSL array of struct members locations
it helps some times Your first example uniform struct MyStruct is a raw uniform whose member locations are arbitrary and must be queried:
TAG : opengl
Date : January 12 2021, 07:00 PM , By : wraith
Will GLSL compiler remove unnecessary variable initialization?
Will GLSL compiler remove unnecessary variable initialization?
wish help you to fix your issue What the compiler has to optimize is not specified in the specification.The only thing what is specified is the behavior of active program resources. See OpenGL 4.6 Core Profile Specification - 7.3.1 Program Interfaces
TAG : opengl
Date : January 12 2021, 01:40 AM , By : Xander
Object disapear/don't scale in the Z-AXIS of OPENGL
Object disapear/don't scale in the Z-AXIS of OPENGL
should help you out Help stamp out GL_PROJECTION abuse.
TAG : opengl
Date : January 10 2021, 01:49 PM , By : geo
Same program, target both Open GL and Open GL ES 2.0
Same program, target both Open GL and Open GL ES 2.0
Does that help OpenGLES is (more or less) a stripped down version of OpenGL (which mainly removes the old legacy cruft, and any features that may hurt battery life). There are a few very minor differences here and there, but that's largely the case.
TAG : opengl
Date : January 06 2021, 03:17 PM , By : Sanoran
How to tile part of texture in fragment shader
How to tile part of texture in fragment shader
will help you So I got help in Defold community and ended up with fragment shader like this:
TAG : opengl
Date : January 02 2021, 06:48 AM , By : Mike
Do I need output gamma correction in a fragment shader?
Do I need output gamma correction in a fragment shader?
I hope this helps you . Every fragment shader output is routed to a specific image in the framebuffer (based on glDrawBuffers state). That image has a format. That format defines the default colorspace interpretation of the corresponding output.There
TAG : opengl
Date : January 02 2021, 06:48 AM , By : turret
gl_SubgroupInvocationID numeration in multi-dimensional work-groups
gl_SubgroupInvocationID numeration in multi-dimensional work-groups
may help you . The partitioning of a workgroup into subgroups is implementation defined. Furthermore, you're not supposed to care about it.The purpose of the subgroup functions is to facilitate intercommunication between subgroups. To ask about value
TAG : opengl
Date : January 02 2021, 06:48 AM , By : Jarques
OpenGL overlapping ugly rendering
OpenGL overlapping ugly rendering
Any of those help Solution 1 (not a good one): Applying gl.Scale(0.0001, 0.0001, 0.0001); to the ModelView matrixSolution 2 : The near plane has to be as far as possible to avoid compressing z value in a small range. In this case, use 10 instead of 0
TAG : opengl
Date : January 02 2021, 06:48 AM , By : Asbie
order independent transparency - memory barrier
order independent transparency - memory barrier
seems to work fine For your general question, yes, you need an explicit memory barrier between the two operations.On a more personal note, please stop looking at that code. I'm seeing many dubious things beyond just the lack of a barrier: the mapping
TAG : opengl
Date : January 02 2021, 06:48 AM , By : Si Gardner
How do I prevent jagged edges alongside the surfaces of my 3d model?
How do I prevent jagged edges alongside the surfaces of my 3d model?
around this issue That doesnt look like Z-fighting to me..If you are drawing the flat shaded objects and then some GL_LINES over it, those lines will produce that effect because they are not antialiased.
TAG : opengl
Date : January 02 2021, 06:48 AM , By : alexmajy
What is the PIXELFORMATDESCRIPTOR parameter in SetPixelFormat() used for?
What is the PIXELFORMATDESCRIPTOR parameter in SetPixelFormat() used for?
With these it helps I believe you won't have to use PIXELFORMATDESCRIPTOR and ChoosePixelFormat, just use wglChoosePixelFormatARB and set the returned int as pixelformat. Those functions are used just to query windows for matching pixel format, the S
TAG : opengl
Date : January 02 2021, 06:48 AM , By : Piotr Balas
Dot product in LookAt Matrix implementation
Dot product in LookAt Matrix implementation
To fix the issue you can do The parameters to "lookAt" define the position and orientation of the camera (eye) in the world. A matrix which is set by this parameters would transform form view space to world space. It can take coordinates which are re
TAG : opengl
Date : January 02 2021, 06:48 AM , By : Killercode
How to diagnose in Qt why "unable to open file"
How to diagnose in Qt why "unable to open file"
I hope this helps you . I just tried to run the example on Qt5.13 windows 10 MSVC2017 64 bit without a problem so there must be something else going on here.the same example is already installed in Your Qt installation directory. Can you try it from
TAG : opengl
Date : January 02 2021, 06:36 AM , By : taviso
Why OpenGL use float to define the level of anisotropic filtering?
Why OpenGL use float to define the level of anisotropic filtering?
Hope this helps Because there is no reason not to use a float. The anisotropy more or less represents the aspect ratio of the pixel (or filter) footprint in texture space. (In the most general case of a perspective projection, the pixel footprint wou
TAG : opengl
Date : December 27 2020, 03:55 PM , By : Mariamario
Is it safe to unbind a buffer that is mapped from glBufferStorage after mapping with GL_MAP_PERSISTENT_BIT, and then wri
Is it safe to unbind a buffer that is mapped from glBufferStorage after mapping with GL_MAP_PERSISTENT_BIT, and then wri
wish help you to fix your issue I've been going through online blogs, reading up about glMapNamedBufferRange and glUnmapBuffer, though the docs seem to only mention: , In short, is the above is safe to do?
TAG : opengl
Date : December 26 2020, 01:30 AM , By : John Q.
When applying glScalef() to a polygon, it changes its position, how to get rid of it?
When applying glScalef() to a polygon, it changes its position, how to get rid of it?
it fixes the issue glScalef() doesn't scale a polygon, it scales an entire coordinate system. Everything will be scaled around the point with coordinates (0, 0, 0), not around the center of the polygon.If you want to scale around some other point (x,
TAG : opengl
Date : December 25 2020, 09:01 PM , By : Dave
OpenCL OpenGL interop and Element buffer
OpenCL OpenGL interop and Element buffer
hop of those help? In OpenCL, uint3 is just an alias for uint4, i.e. its size is 4 * sizeof(char). See section 6.1.5. Alignment of Types of the OpenCL specification for more information. You will probably need to use the vload3 instruction.
TAG : opengl
Date : December 23 2020, 05:30 AM , By : zdyne
OpenGL: How to draw multiple line strips in one call?
OpenGL: How to draw multiple line strips in one call?
will be helpful for those in need In OpenGL, draw call overhead is not that high, compared to some other APIs. The issue is the overhead of state changes between draw calls. So the primary goal in terms of optimization should be to reduce the number
TAG : opengl
Date : December 21 2020, 03:06 PM , By : Lars
glm::lookAt returns matrix with nan elements
glm::lookAt returns matrix with nan elements
help you fix your problem The problem is with either your camera's position, or the up vector.Your camera is 1 unit up (0,1,0), looking down at the origin (0,0,0). The up vector indicates the up direction of the camera, not the world space. For examp
TAG : opengl
Date : December 18 2020, 12:00 PM , By : Lars
getting a crash while using glReadPixels to map texture in memory
getting a crash while using glReadPixels to map texture in memory
this will help You are unbinding your GL_PIXEL_PACK_BUFFER before the glReadPixels, so the NULL pointer will be interpreted relative to your client memory address space, and trying to copy the data to there will almost certainly result in a crash.
TAG : opengl
Date : December 16 2020, 02:46 PM , By : CM.
Is there a list of OpenGL extension support?
Is there a list of OpenGL extension support?
To fix the issue you can do There is no general document for extensions support, though some databases are kept largely up to date by communities:https://opengl.gpuinfo.org/listreports.php?extension=GL_ARB_shading_language_include
TAG : opengl
Date : December 15 2020, 09:15 AM , By : Jakub Filak
Why the quads do not render?
Why the quads do not render?
may help you . You can`t "see" the planes because of the Blending.The blend function (see glBlendFunc)
TAG : opengl
Date : December 05 2020, 11:52 AM , By : Joshua Johnson
Million mesh programmatically?
Million mesh programmatically?
like below fixes the issue The simplest way would be to generate a large triangle strip grid, upload it to a VBO and draw it, using the vertex shader to alter just the up coordinate. The vertex shader can also generate normals from the heightmap (or
TAG : opengl
Date : November 28 2020, 08:01 AM , By : Sonal
When are OpenGL object names ever zero? Or, does zero ever have semantics?
When are OpenGL object names ever zero? Or, does zero ever have semantics?
Hope that helps From the OpenGL 4.4 Core Profile Specification:
TAG : opengl
Date : November 26 2020, 01:01 AM , By : cnemelka
Logarithmic depth buffer linearization
Logarithmic depth buffer linearization
it should still fix some issue With logarithmic depth buffer, the mapping of scene (camera space) depth to values that ultimately end up in the depth buffer (0..1) is:
TAG : opengl
Date : November 25 2020, 07:22 PM , By : Thomas Plunkett
Moving sideways using gluLookAt(); C++
Moving sideways using gluLookAt(); C++
I wish did fix the issue. It's unclear where all of the things you have above are happening since you didn't post all of your code and it's cut off in weird places. But if you want to move the camera left and right, it should be fairly easy. The defi
TAG : opengl
Date : November 24 2020, 03:41 PM , By : user121405
glVertexAttribPointer raising impossible GL_INVALID_OPERATION?
glVertexAttribPointer raising impossible GL_INVALID_OPERATION?
I wish did fix the issue. You must have a non-zero Vertex Array Object bound in an OpenGL 3.1 context without the extension GL_ARB_compatibility or a core profile context. This is one of the hidden conditions that will generate a GL_INVALID_OPERATION
TAG : opengl
Date : November 21 2020, 07:35 AM , By : Schmidt
Change vertex colors in vertex buffer object
Change vertex colors in vertex buffer object
fixed the issue. Will look into that further Yes you can. Assuming you do have your data stored in a VBO, you could update select chunks of it by first binding said object and then using glBufferSubData. Take a look here. https://www.opengl.org/sdk/d
TAG : opengl
Date : November 20 2020, 01:01 AM , By : fayoh
Can I redraw only part of a scene in OpenGL?
Can I redraw only part of a scene in OpenGL?
I hope this helps you . Render the static parts to a FBO, blit that as needed to the framebuffer, and render dynamic objects on top.
TAG : opengl
Date : November 19 2020, 12:01 PM , By : alchemist
how to retrieve z depth and color of a rendered pixel
how to retrieve z depth and color of a rendered pixel
Does that help I would like to retrieve the z height of each pixels of a rendered object in a scene. I will need to retrieve the color rendered too. , glReadPixels and CPU side code
TAG : opengl
Date : November 19 2020, 04:01 AM , By : Alex
glow around composited framebuffers
glow around composited framebuffers
Hope this helps For compositing you most likely want to use pre-multiplied alpha to get the effect you want. Either pre-multiply the texture when you upload the data
TAG : opengl
Date : November 18 2020, 03:46 PM , By : Matt
glEnableClientState was not declared in OpenGL v4.5
glEnableClientState was not declared in OpenGL v4.5
wish of those help I am using OpenGL version 4.5.0 and getting this error: ,
TAG : opengl
Date : November 17 2020, 11:01 PM , By : Thx1138.6
QGLWidget not Updating (Pyqt5 and OpenGL)
QGLWidget not Updating (Pyqt5 and OpenGL)
Hope this helps The problem is with the the global variables a and b. They are not being updated in the mouse event callbacks. Try using global a and global b statements in your callbacks. A better approach would be to make these variables as class a
TAG : opengl
Date : November 17 2020, 03:01 PM , By : user143038
VAOs and Element Buffer Objects
VAOs and Element Buffer Objects
Hope this helps From opengl.org:
TAG : opengl
Date : November 16 2020, 09:01 AM , By : Mariamario
mix RGBA pixmap with texture
mix RGBA pixmap with texture
I wish did fix the issue. You can render to a texture with a framebuffer object (FBO).At the start of your program, create an FBO and attach the texture to it. Whenever you need to draw a stroke, bind the FBO and draw the stroke as if you were drawin
TAG : opengl
Date : November 15 2020, 06:54 AM , By : antonio
Cylinder VBO OpenGL: What am I doing wrong?
Cylinder VBO OpenGL: What am I doing wrong?
this one helps. The problem is the size you are passing to glBufferData: sizeof(bufferData) is the same as std::vector and has nothing to do with the size of the vectors data.What you have to do is to pass the actual size of the data stored in the ve
TAG : opengl
Date : November 13 2020, 05:43 AM , By : brij
OpenGL XCode8 Linking Error
OpenGL XCode8 Linking Error
hop of those help? I think this somehow fixed my problem :Dstatic variable link error
TAG : opengl
Date : November 12 2020, 11:01 PM , By : Simone
GLSL complex error: implict cast from vec4 to vec3
GLSL complex error: implict cast from vec4 to vec3
wish help you to fix your issue The problem is that you're using vec3 as third argument into mix(). Which is not correct, as it can be only same type as other arguments' type: vec4() or use primitive type.
TAG : opengl
Date : November 10 2020, 04:01 AM , By : toki
OpenGL - Why are my Z coords 2x scale?
OpenGL - Why are my Z coords 2x scale?
I hope this helps . Transformation matrices are only half of the truth. In modern GL, the vertex shader (or more precisely: all programmable stages before the rasterizer) are responsible for the transformation of object space coordinates into clip sp
TAG : opengl
Date : November 08 2020, 09:00 AM , By : Puneet Madaan
VAO not rendering colors OpenGL?
VAO not rendering colors OpenGL?
fixed the issue. Will look into that further I was hoping to get some help on an OpenGL question concerning the creation and rendering of VAOs. The goal here is simply to take this: , I should also mention that I'm not using a shader program.
TAG : opengl
Date : November 06 2020, 11:01 PM , By : jrf
GLGenVertexArrays giving me an invalid memory address
GLGenVertexArrays giving me an invalid memory address
this will help All functions and extensions of OpenGL > 1.1 have to be loaded in order to be used. This can be done, for example, by using glew which has to be initialized as follows:
TAG : opengl
Date : November 05 2020, 06:58 PM , By : user181945
OpenGL won't render with top left coordinates
OpenGL won't render with top left coordinates
help you fix your problem When changing the orientation of the y-axis, also the winding order of the primitives changes. So if backface culling is enabled, one has to adjust the winding order by setting it with
TAG : opengl
Date : November 05 2020, 09:01 AM , By : 3NZ0
Will any of the following texture lookups cause undefined behavior, non-uniform flow, or both?
Will any of the following texture lookups cause undefined behavior, non-uniform flow, or both?
Does that help I am drawing sprites to the screen using a vertex shader, fragment shader, and a small number of texture atlas (images that contain dozens of smaller sprites). I aim to use a single draw call for the entire scene so need to create a sh
TAG : opengl
Date : November 03 2020, 04:01 AM , By : Ohad Barzilay
Perspective division explanation?
Perspective division explanation?
I hope this helps you . In clip space, clipping is not done against a unit cube. It is done against a cube with side-length w. Points are inside the visible area if each of their x,y,z coordinate is smaller than their w coordinate.In the example you
TAG : opengl
Date : October 31 2020, 04:00 PM , By : T11M
unknown layout specifier 'triangles'
unknown layout specifier 'triangles'
it helps some times According to the standard the only allowed primitive types for outputs are points line_strip triangle_strip
TAG : opengl
Date : October 31 2020, 01:49 PM , By : Guid
Fragment Shader IN variable causes nothing to appear
Fragment Shader IN variable causes nothing to appear
I hope this helps you . int variables cannot be interpolated by the GL. You must declare both the output and the corresponding input with the flat qualifier`.From the behavior you described, it seems like you are not properly checking the compile and
TAG : opengl
Date : October 31 2020, 01:47 PM , By : Elwillow
Stroke and Fill Shapes in Cocos2dx
Stroke and Fill Shapes in Cocos2dx
I think the issue was by ths following , I think CCSprite/CCLayerColor/CCLayerGradient with CCClippingNode can simulate the "smart brush", and tintTo/tintBy action of CCSprite/CCLayerColor can change color without destroying the object
TAG : opengl
Date : October 31 2020, 01:47 PM , By : flesk
Weird result with MSAA
Weird result with MSAA
seems to work fine MSAA only helps to smooth polygon edges and intersections. It does nothing to smoothen sharp transitions created by your shader code.The main idea behind MSAA is that the fragment shader is still executed only once per fragment. Ea
TAG : opengl
Date : October 30 2020, 10:01 AM , By : JSebok
OpenGL How to calculate worldspace coordinates from frustum aligned vectors?
OpenGL How to calculate worldspace coordinates from frustum aligned vectors?
I wish did fix the issue. Well, it is not 100% clear what you mean by "frustum space". I'm going to assume that it does refer to normalized device coordinates in OpenGL, where the view frustum is (by default) the axis-aligned cube -1
TAG : opengl
Date : October 30 2020, 05:01 AM , By : TRobison
Why is scissor test behind fragment operation?
Why is scissor test behind fragment operation?
I wish did fix the issue. The scissor test will in almost any real-world scenario affect the rasterization itself. The GPU's rasterizer units will not produce fragments outside of the scissor rect. When the OpenGL pipeline was first created, the frag
TAG : opengl
Date : October 29 2020, 10:01 AM , By : Liviu Aileni
Build OpenCV 3.0 with OpenGL and GTK on LMDE2 (Debian 8.2)
Build OpenCV 3.0 with OpenGL and GTK on LMDE2 (Debian 8.2)
To fix this issue After reading the cmake script cmake/OpenCVFindLibsGUI.cmake, I've found the related cmake codes:
TAG : opengl
Date : October 28 2020, 05:11 PM , By : Philofax
Use default framebuffer depth buffer in a fbo
Use default framebuffer depth buffer in a fbo
seems to work fine I read and searched but I didn't find how to properly use the default framebuffer depth buffer in another framebuffer
TAG : opengl
Date : October 24 2020, 08:10 AM , By : anon
Colors in OpenGL VBOs?
Colors in OpenGL VBOs?
it should still fix some issue I'm trying to add colors to my object that using a single struct and single VBO in OpenGL. To do this, I have a Vertex struct that I created that looks like this:
TAG : opengl
Date : October 23 2020, 05:39 PM , By : Tetting
raycasting: how to properly apply a projection matrix?
raycasting: how to properly apply a projection matrix?
I hope this helps you . To shoot rays out into the scene, you want to start by putting yourself (mentally) into the world after the projection matrix has been applied. This means that the view frustrum is now a 2x2x1 box - this is known as the canoni
TAG : opengl
Date : October 20 2020, 11:12 AM , By : ArmHead
Equiv of glDrawpixels that operates on GPU memory?
Equiv of glDrawpixels that operates on GPU memory?
it should still fix some issue Let's cover all the bases here.First, a direct answer: yes, there is such a function. It's called glDrawPixels. I'm not kidding.
TAG : opengl
Date : October 15 2020, 11:12 AM , By : Per
How do you determine when an object is drawn on-screen in OpenGL?
How do you determine when an object is drawn on-screen in OpenGL?
Hope this helps You can use the query objects (specifically those object created using GL_ARB_occlusion_query extension Specification). Those object are used to query how many fragments are rendered using a sequence of OpenGL operations (begin/end, e
TAG : opengl
Date : October 14 2020, 01:07 PM , By : Adam Hill
Is it possible to make a free camera in OpenGL?
Is it possible to make a free camera in OpenGL?
Any of those help Yes of course it is possible. Or rather, because there's no camera in OpenGL in the first place any occurrences of gimbal lock are upon whoever wrote the transformation manipulation code.I guess you're using Euler angles (i.e. 3 ang
TAG : opengl
Date : October 06 2020, 12:00 AM , By : fayoh
any Idea howto flip a Mesh to generate an Object?
any Idea howto flip a Mesh to generate an Object?
To fix the issue you can do Scale the mesh by -1 1 1 (to mirror through the x axis), and reverse the face winding via glFrontFace. For example in old school OpenGL:
TAG : opengl
Date : October 05 2020, 01:00 PM , By : Deepak Poondi
glMultiDrawElements and glDrawElements equivalences
glMultiDrawElements and glDrawElements equivalences
wish of those help glMultiDrawElements behaves as if you did those draw calls. Performance is not, and never has been, part of "behavior". The OpenGL specification defines behavior; it does not and cannot specify performance.It should also be noted t
TAG : opengl
Date : October 03 2020, 08:00 PM , By : kbrust
glMultiDrawArraysIndirect and trying to find which draw call it is
glMultiDrawArraysIndirect and trying to find which draw call it is
I hope this helps . If you have GL 4.6/ARB_shader_draw_parameters, then you have access to gl_DrawID, which is exactly what it sounds like: the zero-based index of the draw in any multi-draw command. It's also guaranteed to be dynamically uniform, so
TAG : opengl
Date : October 03 2020, 06:00 PM , By : ┬Áilad

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