gl-shader | WebGL shader wrapper | Graphics library

I tried to run the SSDO demo code from here but met with several problems that confused me even further after I had spent hours searching for solutions. Nevertheless, now I am almost certain that the problems are with the GLSL version.

Note that:

• The demo uses glew and glut.
• My environment is Microsoft Visual Studio Community 2019 on Windows 10 pro supported by Parallels Desktop on a 15" MacBook Pro 2018.

Before any modifications to the code, I got a bunch of error messages:

I have a project which uses about 2 dozen .vsh and .fsh files to draw 2D tiles using OpenGLES. Since that is deprecated, I want to convert my project to Metal. My head is now swimming with vocabulary and techniques involved in both systems - graphics is not my forte.

Can I use OpenGLES to compile the .vsh/.fsh files, and then save them in a metal-compatible format? The goal would be to then use the saved information in a metal-centric world and remove all the OpenGLES code from the project. I've spent a few days on this already, and yet I don't understand the processes enough to fully attempt the transition to Metal. Any/all help is appreciated.

I saw this: "On devices that support it, the GLSL code you provide to SKShader is automatically converted to Metal shading language and run on a Metal renderer", which leads me to believe there is a way to get this done. I just don't know where to begin. OpenGL ES deprecated in iOS 12 and SKShader

I have seen this: Convert OpenGL shader to Metal (Swift) to be used in CIFilter, and if it answers my question, I don't understand how.

I don't think this answers it either: OpenGL ES and OpenGL compatible shaders

Answers/techniques can use either Objective-C or Swift - the existing code is Objective-C, the rest of the project has been converted to Swift 5.

I tryed to put data in the fragment shader to color 2 triangles through textures, but the color given is black (maybe default?), not green or red as expected.

The source from where I tryed to do that is https://webglfundamentals.org/webgl/lessons/webgl-shaders-and-glsl.html#textures-in-fragment-shaders. I put everything from there in my source and I thought that if I put a green pixel with a red pixel in my texture, then it needs to have a different color than black, but was black.

That's the fragment shader:

I have a project* in which I play two videos, run a simple shader that shows edges and blends them, and display the result in a canvas. The project is based on this tutorial. The goal I try to achieve is to understand whether running on JS and WebAssembly is faster than just WebGL work in JS, but at the moment I'm switching between JS and WebAssembly on every frame, which seems to be very expensive.

In every frame the code copies the content of each HTMLVideoElement into a WebGL texture in JS:

Just focusing on the uniforms/attributes/varyings for a single vertex/fragment shader pair, I'm wondering how you might model the following system using textures. Focusing on 2D.

• position: The current object's position.
• translation: The objects proposed next position based on some CPU calculations up front.
• velocity: The objects velocity.
• rotation: The objects next rotation.
• forces (like gravity or collision): The object's summed forces acting on it in each direction.
• temperature: The object's temperature.
• mass/density: The object's mass/density.
• curvature: Moving along a predefined curve (like easing).

At first I wanted to do this:

Wondering if it's possible to pass a large array into a WebGL shader, like this:

An OpenGL project can't display any object anymore. I tried to remake everything from scratch but it still doesn't works.

Main Code

I couldn't find anything about this so here goes: What I'm trying to do is make a generic game engine, I want to be able to load any 3D object and apply any shader to that model.

I'm at the point where I need to know where the vertex attributes in the shader are so I can feed them to glVertexAttribPointer, However, glVertexAttribPointer takes as input the location of the attribute. Different shaders could have different locations for the vertices. Is there a way to query the attributes in a shader and store them in a list in c++?

Post Answer: I've found the following answer that explains it in more detail.

Details: I have a glsl fragment shader with a uniform texture, "u_MapTexture" with several thousand colors on it (max of about 10k-15k unique rgb values). I also have a uniform palette texture ("u_paletteTexture") that is 16384 × 1 that I want to use to index the colors on u_MapTexture to. My problem is that no matter what I try mathematically, I can't seem to properly index the colors from the first texture to the palette texture using the RGB values of the passed color. Amy thoughts or ideas as to how I could do this?

Wasn't sure whether to post this here, on Gamedev SE, or on the Math SE.

Edit: I guess I might not have added enough information about the problem in, so here are some more details.

My current idea for the map is to keep an indexed palette of province colors, and to perform a palette-swap operation in my fragment shader (like the one outlined in this SO question: Simulating palette swaps with OpenGL Shaders (in LibGDX)). My shader is pretty much exactly copied from the linked article.

My problem: finding a way to uniquely index the province map (the original texture) -> province colors (the indexed palette texture).

At first, I decided that the palette texture would be configured as a (255+255)×(255+255) texture. This would give a large maximum number enough number of countries to choose from that would never in practice be reached.

I thought you could get the appropriate index of the palette texture of a country's color by getting its index in the texture as so: the index of each country would have been located at that palette texture's (x, y)->(r+g),(g+b)

I ran some example colors through this simple equation and came across a troubling scenario: