Blender Tutorial: Coloring and Rendering Donuts

Coloring Sprinkles

• Traditional Method (Not Recommended):

  • Manually selecting each sprinkle and assigning a color.
  • Issues:
    • Color is locked to each sprinkle.
    • Difficult to change color distribution.

• Efficient Method:

  • Create a single material (e.g., "sprinkles").

  • Apply the material to multiple objects simultaneously.

    • Shift select all objects, then select the object with the desired material last.
    • Press Ctrl + L and choose "Link Materials".

  • Shading Tab Setup:

    • Add an "Object Info" node and use the "Random" output.
    • Converting random values to color using a ColorRamp node:
      • Linear to constant to ensure consistent colors for each sprinkle.
        • Example: Light blue, purple, pink, white, yellow.
      • Adjust color distribution easily.

  • Adding Metallic Sprinkles:

    • Use the "Metallic" slider in the Principled BSDF shader.
    • Typically, values should be either 0 (non-metallic) or 1 (metallic).
    • Create another ColorRamp for metallic properties (black = non-metal, white = metal).
    • Adjust roughness for realistic metallic look.

Rendering the Scene

• Camera Adjustment:

  • Use Shift + ~ (fly mode) for camera positioning.
  • Navigate like a video game (W, A, S, D for movement; E for up, Q for down).

• Render Engines:

  • Eevee (real-time, rasterized engine):
    • Fast but not very accurate for realistic lighting and shadows.
  • Cycles (path-traced, offline renderer):
    • Accurate with realistic bounce lighting and shadows.
    • Utilizes CPU or GPU (enable in Preferences: CUDA for NVIDIA, HIP for AMD).
    • Performance enhancements using GPU and denoise techniques.

• Adjusting Scene Lighting:

  • Adjust light position and strength for better shadow effects.
  • Use Alt + G to reset object positions.

Subsurface Scattering (SSS)

• Importance:

  • Adds realism by allowing light to pass through objects like icing or flesh.
  • Adjust subsurface settings in the material properties.

• Setup:

  • Set "Subsurface" to a relevant weight (commonly 1 for SSS objects).
  • Adjust radius values to 1, 1, 1 (RGB channels).
  • Set subsurface scale based on object thickness.

• Sprinkles SSS:

  • Similar approach with low scale values (e.g., 0.02).
  • Metallic sprinkles automatically negate SSS effect.

Homework Assignment

• Model a Plate:
  • Use the techniques learned to attempt modeling a plate.
  • Apply the previous tools and skills for hands-on learning.
  • Reference upcoming video for solutions if necessary.