\( \newcommand{\vecIII}[3]{\left[\begin{array}{c} #1\\\\#2\\\\#3 \end{array}\right]} \newcommand{\vecIV}[4]{\left[\begin{array}{c} #1\\\\#2\\\\#3\\\\#4 \end{array}\right]} \newcommand{\Choose}[2]{ { { #1 }\choose{ #2 } } } \newcommand{\vecII}[2]{\left[\begin{array}{c} #1\\\\#2 \end{array}\right]} \newcommand{\vecIII}[3]{\left[\begin{array}{c} #1\\\\#2\\\\#3 \end{array}\right]} \newcommand{\vecIV}[4]{\left[\begin{array}{c} #1\\\\#2\\\\#3\\\\#4 \end{array}\right]} \newcommand{\matIIxII}[4]{\left[ \begin{array}{cc} #1 & #2 \\\\ #3 & #4 \end{array}\right]} \newcommand{\matIIIxIII}[9]{\left[ \begin{array}{ccc} #1 & #2 & #3 \\\\ #4 & #5 & #6 \\\\ #7 & #8 & #9 \end{array}\right]} \)

Quiz

  1. will there be a library of materials that we can access, like with the colors.

    No, but a material is usually a color plus some other settings, so a library of colors is mostly what you need.

  2. In what cases would the specular reflection not be white while the light being reflected is white?

    Interesting question! Usually, we think of a specular reflection as being mirror-like, so that the reflected light is the same as the incoming light. So a red spotlight on a shiny green sequin reflects as red light.

    But, you don't need to do that. Maybe you have something a little less shiny than the sequin, but still reflective. (Satin?) Maybe it contributes a bit of color, so that the specular reflection is a combination of its color and the light's color.

    You can do that in the Phong model, but having a non-white color as the specular color.

    Note that the combination is multiplication, not addition, so red+green=yellow but red*green=(1,0,0)*(0,1,0)=black. But yellow*cyan=(1,1,0)*(0,1,1)=green.