Vulkan Tutorial (official Khronos edition)
The Khronos Group
Khronos-maintained walkthrough of explicit GPU programming against Vulkan 1.4: instances, devices, swapchains, pipelines, command buffers, vertex and uniform buffers, textures, depth, mipmaps, multisampling and compute shaders, using dynamic rendering, Slang shaders and C++20 RAII bindings.
More resources on Computer Graphics
Real-Time Rendering (4th edition)
Reference volume for real-time graphics engineers: the GPU pipeline, transforms, shading and BRDF models, texturing, shadow techniques, global illumination approximations, acceleration and culling, image-space effects and hardware architecture, with an extensive cited literature survey in every chapter.
Fundamentals of Computer Graphics (5th edition)
The reference text for the mathematical core of the field, and the book to reach for when a lecture derivation needs backing. This standard university textbook, teaching ray tracing and rasterisation side by side. Covers vectors and matrices, viewing transformations, sampling and antialiasing, texture mapping, spatial data structures, splines, colour science and animation; the fifth edition rewrote the shading, reflection and path-tracing chapters.
Physically Based Rendering: From Theory to Implementation (4th edition, free online)
Complete text of the fourth edition, free online. Presents the pbrt renderer as literate code alongside the theory: radiometry, BSDFs, sampling and reconstruction, Monte Carlo integration, light transport algorithms, volumetric scattering, and a chapter on GPU ray tracing.
Ray Tracing in One Weekend (book series)
The universally cited free on-ramp to offline rendering: short enough to finish, but it ends with real Monte Carlo estimator maths, so it is a genuine bridge into PBRT rather than a toy. Three short public-domain books that go from a blank C++ file to a working path tracer: spheres, surface normals and cameras; then diffuse, metal and dielectric materials; then motion blur, BVH acceleration, volumes and Monte Carlo estimator theory.
Introduction to Computer Graphics (University of Utah, Cem Yuksel)
The strongest free entry point: a real semester course, not a tutorial series, so it builds the mathematical foundation (transformations, projection, shading models) that tutorial sites skip. Recorded University of Utah lecture course covering the rasterisation pipeline, transformations and projections, clipping, visibility, shading models, texturing, curves and surfaces, and ray tracing, with the underlying linear algebra derived on the board rather than assumed.