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Once Upon a Pixel: How Crysis Changed Real-Time Lighting Forever

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Description

Once Upon a Pixel: How Crysis Changed Real-Time Lighting Forever is an OGLDEV YouTube tutorial that teaches Screen Space Ambient Occlusion (SSAO) through Crytek's Crysis-era work, then implements it in OpenGL.

It reviews ambient lighting limits, Vladimir Kajalin's per-pixel screen-space approximation, and later variants such as HBAO and GTAO. The walkthrough builds lighting and occlusion framebuffers, depth linearization, hemisphere samples in tangent space, random rotation textures, Gram-Schmidt tangent frames, radius and attenuation controls, and a combine pass, following a 3D Graphics Rendering Cookbook OpenGL path with small extras.

It is for intermediate graphics programmers comfortable with OpenGL framebuffers and fullscreen passes who want a working SSAO baseline.

Access is a free long-form video with code-oriented explanation on the OGLDEV channel.

It is useful as a concrete SSAO implementation guide that connects the historical technique to shaders you can later port toward Vulkan.