Скачать или смотреть How to Convert Shader Source to const char for OpenGL in C

Learn how to read shader source code from a file in C and pass it as `const char *` to OpenGL's `glShaderSource` function.
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This video is based on the question https://stackoverflow.com/q/77732135/ asked by the user 'alaanvv' ( https://stackoverflow.com/u/21266942/ ) and on the answer https://stackoverflow.com/a/77732296/ provided by the user 'Eric Postpischil' ( https://stackoverflow.com/u/298225/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Handling OpenGL Shader Sources in C: Reading from Files

When working with OpenGL in C, one common challenge developers face is how to manage shader source code effectively. Traditionally, shader source code is defined as a constant string within the program itself. However, as development leads to more complex applications, it becomes necessary to manage shaders through external files. This guide addresses this issue by walking through a solution to read shader files and pass their contents into OpenGL's shader creation functions.

The Problem

Imagine you have a simple shader defined in your code like this:

[[See Video to Reveal this Text or Code Snippet]]

This works well, but what if you want to store your shader code in a separate file? You might create a function like the following to read the shader from a file, but you're met with an error regarding the expected data type for glShaderSource. The function tries to pass a char array, but OpenGL expects a const char * const *. Here's a snippet of the problematic code:

[[See Video to Reveal this Text or Code Snippet]]

The Solution

It can be tricky to manage the types when dealing with buffer arrays. However, there's a straightforward workaround. The goal is to convert your array into a pointer type that OpenGL's glShaderSource function can accept safely.

Step-by-Step Instruction:

Reading the Shader File: You correctly open a file and read its content into a character buffer, but there's a small misalignment with how you define and pass it.

Defining the Array: While you may define char vertex_shader_source[size];, ensure that the proper null terminator is added after reading the content.

Creating a Pointer: Create a pointer of type const char* that points to the first element of your shader source buffer. You can do this using either a compound literal or a separate variable.

Example of using a compound literal:

[[See Video to Reveal this Text or Code Snippet]]

Correctly Passing the Pointer

Now, when you pass it into the glShaderSource function, do the following:

[[See Video to Reveal this Text or Code Snippet]]

This ensures that you are using a pointer-type that OpenGL expects, resolving the type mismatch error.

Complete Example

Here’s what the shader loading function may look like after fixing the issue:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By converting the data type correctly and ensuring buffers are managed, you can successfully load shaders from files without encountering type mismatch errors in OpenGL. This approach not only adheres to safety concerning data types but also fosters cleaner and more maintainable code as your project grows.

Implementing this kind of structure ensures your code is adaptable, encouraging best practices throughout your game or graphics application development.

That's it! With this knowledge, you're equipped to seamlessly manage OpenGL shaders from external files in your C applications.