![]() POM is great however as it looks so far, the problem is that the implementation was very difficult and still postponed. Indeed you are not restricted to think only about how to calculate normals for triangles, but go directly to the interesting raytracing techniques at once (normal+lightbounce+etc…). Unless for example you want to lock the code design into some specific technique then you follow these principles by intent. Vs_out.TangentFragPos = TBN * vs_out.Yet as far as I know that’s the best we got for now.Īs for example if you write shader code, the boundaries between raytracing/volumetric/polygon all blend together (all techniques and principles can be or can’t be the same technique). Vec3 N = normalize(mat3(model) * aNormal) Vec3 B = normalize(mat3(model) * aBitangent) Vec3 T = normalize(mat3(model) * aTangent) Vs_out.FragPos = vec3(model * vec4(aPos, 1.0)) Gl_Position = projection * view * model * vec4(aPos, 1.0) ![]() Layout (location = 4) in vec3 aBitangent Layout (location = 2) in vec2 aTexCoords ![]() In the normal mapping chapter we already had a vertex shader that sends these vectors in tangent space so we can take an exact copy of that chapter's vertex shader: Here the rough red line represents the values in the heightmap as the geometric surface representation of the brick surface and the vector \(\color\) so we need the view position and a fragment position in tangent space. To understand how it works, take a look at the following image of our brick surface: The idea behind parallax mapping is to alter the texture coordinates in such a way that it looks like a fragment's surface is higher or lower than it actually is, all based on the view direction and a heightmap. This brick surface shown is rendered with parallax mapping, a displacement mapping technique that doesn't require extra vertex data to convey depth, but (similar to normal mapping) uses a clever technique to trick the user. What if we could somehow achieve similar realism without the need of extra vertices? In fact, what if I were to tell you that the previously shown displaced surface is actually rendered with only 2 triangles. As each flat surface may then require over 10000 vertices this quickly becomes computationally infeasible. For instance, taking a flat plane displaced with the above heightmap results in the following image:Ī problem with displacing vertices this way is that a plane needs to contain a huge amount of triangles to get a realistic displacement, otherwise the displacement looks too blocky. When spanned over a plane, each vertex is displaced based on the sampled height value in the height map, transforming a flat plane to a rough bumpy surface based on a material's geometric properties. An example height map derived from the geometric properties of a simple brick surface looks a bit like this: Such a texture that contains height values per texel is called a height map. One way to do this, is to take a plane with roughly 1000 vertices and displace each of these vertices based on a value in a texture that tells us the height of the plane at that specific area. Parallax mapping is closely related to the family of displacement mapping techniques that displace or offset vertices based on geometrical information stored inside a texture. Note that getting an understanding of normal mapping, specifically tangent space, is strongly advised before learning parallax mapping. While parallax mapping isn't necessarily a technique directly related to (advanced) lighting, I'll still discuss it here as the technique is a logical follow-up of normal mapping. While also an illusion, parallax mapping is a lot better in conveying a sense of depth and together with normal mapping gives incredibly realistic results. Just like normal mapping it is a technique that significantly boosts a textured surface's detail and gives it a sense of depth. Parallax mapping is a technique similar to normal mapping, but based on different principles. Parallax Mapping Advanced-Lighting/Parallax-Mapping
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