VGL360

Why triangles?

Triangles are the universal primitive of real-time graphics for three reasons: Always planar. Three points define exactly one plane — no ambiguity about the surface between them. A quad's four points can be non-coplanar, making interpolation undefined without splitting into triangles first. Always convex. Any point inside a triangle can be expressed as a weighted average of its

How to debug shaders?

Step 1 — check compilation and link errors Every shader object and program must be checked for errors after compilation and linking. Many shader bugs produce silent failures — the draw call just does nothing, or outputs black.

What is a vector?

A vector is a direction with a magnitude (length). In 3D graphics you use them to represent positions, directions, and surface orientations. A vector written as (x, y, z) points from the origin to that coordinate.

What is a texture?

At its simplest a texture is a 2D grid of pixels (called texels) stored on the GPU. When the fragment shader runs for a pixel on screen, it can sample the texture — asking "what colour lives at this position?" — and use that value for lighting, colour, roughness, normals, or anything else. The same mechanism handles many map types: albedo (base colour), normal, roughness, metallic, ambient occlusion, emissive.

What is the depth buffer?

After the fragment shader runs, the GPU compares the fragment's depth value against what is already stored in the depth buffer for that pixel. If the new fragment is closer to the camera it passes and the depth buffer is updated. If it is farther away it is discarded. Depth values are normalised to the range 0.0 – 1.0, where 0.0 is the near plane and 1.0 is the far plane.