How to Engrave Glass in Blender: Part 2
In the second part of our glass tutorial we'll learn how to set up and render a realistic glass shader in Blender, and discover how to enrich our scenes with some simple cloth simulation. Be sure to read the first part of this tutorial before starting.
Lighting and Scene Setup
For this scene we will use the classic 3-point lighting in a light box. Add a plane on the top of the glasses and set it as an emission shader (strength 1.5). Add an emission plane on the left side (warm light, strength 1) and another on the right side (cold light, strength 2). Now add some planes and create a light box. Set the material as a white diffuse shader.
Glass and Wine Materials
Select Cycles as the render engine and in Object mode, select a glass and add a new material. Use a glass shader, with the index of refraction set to 1.47 and color RGB (0,99; 0,99; 0,99). Add another material to the object (with the same glass shader) and call it "engraved_glass". Add to the engraved_glass material the texture created in step 4 and connect the texture node to the displacement material output.
I usually use a math node to adjust the displacement level. In Edit mode, select the areas where you want the engravings and click Assign to the Material. If you want to change the size of the texture, add a node map.
Now select the wine material and use a glass shader with IOR set as 1.33, and color red.
Now we'll add a small cloth simulation to our render. Search online to find a fabric texture (or create one with the internal render engine) and save it. Add a plane, and in Edit mode, subdivide it 5 times. From the top view (7 key) go to U key > Unwrap from View.
Add a diffuse material and use the fabric texture as the color input. In the Physics panel, enable Cloth, select Cotton from the preset materials and turn on Self Collision. Select the plane under glasses and in the Physics panel, set it to Collision. Rotate the cloth by 90 degrees and bake the simulation.
Place the glasses in your scene using your creative eye, and then add an empty object - call it "track". Select the first camera and then the empty object, and click Ctrl + T > Track to Constraint. Now the camera should point to the empty object.
Add a second empty object (focus) and place it on the subject you want to focus on. In the Render Layer tab, turn on the Direct Glossy channel and in the Render tab, set Render Samples to 1000 and Resolution to 1920 x 1920. Select the camera, open the Object Data panel and select Focus in the Depth of Field tab. Set Radius as 0.05 and Blades to 5. In the World tab, set Strength as 0. Now press F12 and wait for the end of render (coffee time!)
Open you've composited your image in GIMP, adjust the Levels and Curves, add a new layer with glossy direct image, and set the blending mode to Addition. I usually use an airbrush and a dirty texture to improve the realism of my images. Add your signature, et viola!
Top Tip: Glass Shader and Render Bounces
When we have a glass material in a render we must set light bounces in the Render tab as the number of surfaces that light has to cross. In the image we have 5 glass meshes; if we want the light passes to go through all 5 surfaces we must set bounces as 5 x 2 = 10.