Tools & Environment Setup
3.1 Zero-install options (start here)
Shadertoy (shadertoy.com) write fragment shaders in the browser; huge gallery
The Book of Shaders editor (editor.thebookofshaders.com)
GLSL Sandbox, twigl, KodeLife Three.js / regl / p5.js playgrounds WebGL with custom shaders
3.2 Desktop development
OpenGL: C/C++ with GLFW (window/context), GLAD/GLEW (function loader), GLM (math library). Or Python (moderngl, PyOpenGL), Rust (glow, glium), Java (LWJGL), C# (OpenTK, Silk.NET).
Vulkan: Vulkan SDK (LunarG) includes glslangValidator, glslc (shaderc), spirv-cross, spirv-val, validation layers.
glslViewer — command-line live viewer for fragment shaders.
3.3 Editors & validation
VS Code extensions: *Shader languages support*, *GLSL Lint* (uses glslangValidator), *glsl-canvas* (live preview).
glslangValidator shader.frag — reference compiler/validator from Khronos.
RenderDoc — frame debugger (inspect draw calls, textures, shader inputs/outputs; step through shaders).
Vendor tools: NVIDIA Nsight Graphics, AMD Radeon GPU Profiler, Intel GPA, Xcode GPU tools (Metal), Spector.js (WebGL).