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I am working on a project, where I need to replace the renderings by pybullet with renders generated with pytorch3d.

I figured out that pybullet and pytorch3d have different definitions for the coordinate systems (see these links: pybullet, pytorch3d; x and z axes are flipped), and I accounted for that in my code. But I still have inconsistency in the rendered objects. I thought the problem could be that while pytorch3d expects a c2w rotation matrix (i.e. camera to world), pybullet could probably expect a w2c rotation matrix. However, I cannot find any documentation related to this. Has anyone ever encountered this problem, or maybe can give some useful hint on how to find out what exactly pybullet expects its rotation matrix to be?

Thanks!

I'm fairly new to OpenGL and I tried recreating the tutorial from https://learnopengl.com/Getting-started/Hello-Triangle to draw a rectangle in PyOpenGL.

(Original source code: https://learnopengl.com/code_viewer_gh.php?code=src/1.getting_started/2.2.hello_triangle_indexed/hello_triangle_indexed.cpp)

The first part of the tutorial that only draws a triangle using glDrawArrays works perfectly but when I try to use glDrawElements nothing is drawn. It doesn't even raise an error, it just shows me a black screen. I'm pretty sure I copied the instructions from the tutorial one by one and since there is no error message, I have no idea what I did wrong.

I would appreciate any sort of help.

My code:

Let's first acknowledge that OpenGL is deprecated by Apple, that the last supported version is 4.1 and that that's a shame but hey, we've got to move forward somehow and Vulkan is the way :trollface: Now that that's out of our systems, let's have a look at this weird bug I found. And let me be clear that I am running this on an Apple Silicon M1, late 2020 MacBook Pro with macOS 11.6. Let's proceed.

I've been following LearnOpenGL and I have published my WiP right here to track my progress. All good until I got to textures. Using one texture was easy enough so I went straight into using more than one, and that's when I got into trouble. As I understand it, the workflow is more or less

• load pixel data in a byte array called textureData, plus extra info
• glGenTextures(1, &textureID)
• glBindTexture(GL_TEXTURE_2D, textureID)
• set parameters at will
• glTexImage2D(GL_TEXTURE_2D, ... , textureData)
• glGenerateMipmap(GL_TEXTURE_2D) (although this may be optional)

which is what I do around here, and then

• glUniform1i(glGetUniformLocation(ID, "textureSampler"), textureID)
• rinse and repeat for the other texture

and then, in the drawing loop, I should have the following:

• glUseProgram(shaderID)
• glActiveTexture(GL_TEXTURE0)
• glBindTexture(GL_TEXTURE_2D, textureID)
• glActiveTexture(GL_TEXTURE1)
• glBindTexture(GL_TEXTURE_2D, otherTextureID)

I then prepare my fancy fragment shader as follows:

I'm currently learning OpenGL by this resource and the "Core-profile vs Immediate mode" chapter confused me by the next question.

If the old OpenGL versions (< 3.0) used immediate mode making the user (application) describe the building of a scene, and newer versions (>= 3.0) tried to abstract from it by using VBO and shaders as the only way to describe graphics, is it correct to say that core-profile in OpenGL 3.2+ makes OpenGL libraries based on a retained mode pattern, as the VBO data is something that is not stored by the user (application), therein not letting to describe how to build the scene?

I also can't understand - does adding VBOs in OpenGL 1.4 (maybe 1.5, I'm not sure already) makes these specifications based on a retained mode?

And so, is it correct to say that in OpenGL 3.2+ core-profile is based on retained mode and compatibility-profile is a mix of immediate and retained mode functionality?

My understanding of immediate and retained mode definitions:

• Immediate mode is an API design pattern, which is characterized by a direct call from the application of rendering functions, and each frame with objects displayed on it is drawn from scratch from the data that the user passes to the renderer.

• Retained mode is an API design pattern, which is characterized by an application describing objects that should be rendered in the scene without calling the rendering functions directly - the graphics library is responsible for displaying and converting the data of the displayed objects.

Feel free to indicate any inaccuracies or ambiguities.

I tried to use FFmpeg to capture frames rendered by OpenGL. The result is a .mp4 file for playing back purposes. It works since I got the .mp4 I expected, however the quality is quite low compared to the one rendered by OpenGL. Can anyone tell me why? And How can I adjust my code to make the mp4 of the same quality as the original frames generated by OpenGL?

The result I've got:

images OpenGL vs FFmpeg

Here is my simple code:

As I understand it (correct me if I'm wrong) I can share data between a compute shader and a vertex shader by binding both to the same buffer.

The vertex program is able to display my particles which are drawn as points but they are not being updated by the compute shader. I assume that I've simply missed something obvious but I can't for the life of me see it.

Fragment Shader:

I am a newbie of OpenGL. I am trying to update some variables of a constant block. For example, I have a block like(Copied from opengl learnopengl.com):

I'm trying to learn OpenGL in C++. To clean up my code I was trying to create an header file with all variables, which decribe objects, in it. This header looks something like this:

I have a small opengl world where I tried making a small cube with model matrix and rotating it around the origin axis. I simply got almost everything right but my problem is that whenever I try to chain the rotations .i.e. (rotating on x-axis once and y-axis next without resetting the matrix) I don't get what I wanted. I wanted the cube to rotate on a fixed axis but the cube rotates in its own axis. I mean to say that I want to rotate using the origin's axis but the model rotates using its own axis, the axis stays on the origin but it kinda rotates with the model. I thought my camera was moving not the model but when I try using multiple boxes it proved that my camera was on its own position. I cant figure out how to make the correct rotations. Here's my code for what I did(some codes are from learnopengl.com):