Tag Archives: Parallax Mapping

Blurring the parallax

Today I have published the first demo making use of my new C++ class library, I designed it to be very easily ported to a strict GL3 profile or to ES 2.0.

From plain rendering to depth of field

From plain rendering to depth of field

As a matter of fact, it doesn’t make use of fixed pipeline or deprecated functions at all:

  • No immediate mode, only VBOs
  • No use of OpenGL matrix stacks, I have my classes handling transformations and passing matrices to shaders directly
  • No OpenGL lighting, only per-fragment one
  • No quads or polygons, just triangles
Normal versus parallax mapping

Normal versus parallax mapping

I couldn’t release something only to show changes “under the hood”, I had to make something cool, so I decided to mix together parallax mapping (that, as you can see in the screenshot, is a lot more pronounced now) and depth of field, with the little addition of Stanford PLY mesh loading. 😀

Mr.Fixit model and maps (the character players portray in Sauerbraten) are courtesy of John Siar, thank you John. 😉

As usual, you can have a look to Vimeo videos (640×480, 1280×720) and download the sources.

Parallax mapping for the masses

I have spent the last ten days studying hard, reading the first half of the Orange Book (it’s the last book in the list, of course 😀 ), a plethora of papers, many demos code, tons of tutorials and guides, but at last I achieved what I would have never imagined just two weeks ago. 😉

Fixed Pipeline

Per-pixel Lighting

Normal Mapping Parallax Mapping

The GLSL_parallax demo shows per pixel Blinn-Phong shading, specular mapping and tangent space parallax mapping with offset limiting! 😀

Actually I’m not really sure about the correctness of my implementation (especially regarding tangent space lighting) but screenshots demonstrate that I’m close to it.
In the first one the usual and boring OpenGL fixed functionality per-vertex lighting (ambient, diffuse and specular components of a point light with attenuation), in the second one shaders are enabled, but only to calculate lighting on a per-pixel basis. At last, the third and the fourth image show normal and parallax mapping.

Talking in more detail, the code is written for OpenGL 2 only, it makes use of Vertex Buffer Objects and GLSL shaders using core functions.

Here is the magic:

if (withParallax == true) { // alpha channel encodes the height map
  height = scale * texture2D(Tex1, gl_TexCoord[1].st).a - bias;
  TexCoord = gl_TexCoord[0].st + height * ecPos.xy;
if (withNormal == true)
  nor = 2.0 * normalMap.rgb - 1.0; // decoding normal map

Some statistics:

  • 6 varying variables
  • 7 uniform variables (texture samples and enable/disable booleans)
  • 3 texture fetches every fragment processed
  • (24×3)x3 + 24×2 = 432 floats (1728 bytes) stored in VBOs

Enjoy the shaders! 🙂