For Blender: 2.32 - Version française disponible(fr)

Preliminaries

As well as anything related to raytracing with Blender, because of the supplementary calculus time required by your computer, raytracing is only an option that you should feel free to activate and deactivate. This is done by the mean of the Scene menu (F10 key). The Render tab shows a button labeled Ray you will have to activate in order to use raytracing in your pictures. If you do so, you can deactivate the EnvMap button, even if this one shouldn't bother you if you don't.

scene

The Mirror Transp tab

This tab is divided into two parts, the first one being about reflection (Ray Mirror) and the second being about transparency(Ray Transp). We will pay attention to the first one, here. When activating the Ray Mirror button, you can make use of reflection options for the shader of your object. Its surface will reflect its environment at rendering time; the other buttons and sliders are here to help you controling this reflectiveness.

mirror-opt

  • RayMir:

By default, this value is set to 0.00, which is no reflection at all. By increasing this value up to the maximum (1.00), your object will have the same reflectivity as a perfectly polished mirror. Please note that the reflected colors are strictly those of the original environment, whatever is the base color of your object.

  • Depth:

In our reality, reflecting objects located near each other will reflect themselves up to infinity, and it is possible to spot in the reflects of one, the reflects of the others. Unfortunately, this behavior will require an infinite time of calculus to reproduce. Most of the time, you only need a recursivity level of two or three to get visually attractive results; because of this, the default value is set to 2. Beware: if you foolishly increase the value of this parameter, you will suffer from from drastically longer rendering time if you have many reflective objects in your scene.

  • Fresnel:

Let's undertake a small experimentation in order to understand this parameter. After a rainy day, go out and stand over a puddle of water. You can see the ground under the puddle. Now, please kneel just in front of the puddle, your face close to the ground, and look again at the puddle of water. The liquid surface part which is closer to you lets you see the ground, but if you move your glance toward the other end of the puddle, then the ground is gradually masked until all you see id the reflection of the sky. This is the Fresnel effect, and this option sets how much of the surface is effected by it; with a 0.0 value, the surface is 100% reflective, even if the casual observer is glancing from above, and with a 1.0 value, it shows only the natural shader of the object.

  • Fac

This option sets the intensity of the Fresnel effect.

Fresnel effect example

The animated picture below shows many reflecting objects: two spheres and a cube, but most of all, a transparent water plane on which we will apply the Fresnel Parameters: Fresnel 1.00 and Fac: 1.50. It shows quite well the Fresnel effect: when the angle of view of the camera is close to the angle of the horizontal plane, then we can only barely spot the ground and on the counterpart, we see easily the reflection of the sky on the liquid. But when the camera is at the apex of the water plane, it's mainly the ground of the puddle that can be seen.

fresnel-effect

Check the attached files in order to download the source file.

Colored reflections

In the Shading menu (F5 key), the Material tab lets you define the color effects of three distincts properties: Col simply colors your object; Spe rather gives a hue to the specular spots on the object; finally, Mir gives a slight color to the reflexion of the object. By default, Mir is pure white, which is quite perfect for chrome effects.

colored-reflection

This way, if you'd prefer that your object looks like gold rather than chrome, then you will have to adjust the Col, Spe and Mir properties more accordingly for such a material.

gold-test

The result is rather obvious:

QuickGold_OrRapide