Arithmetics

Let's take a break and do something simpler in this exercise: math. So far we learned how to declare stuff and move data around. But what if we wanted to actually do something? Luckily doing things is simpler than setting things up!

In this exercise, you are pretty much free to do whatever you want. In exercise.spvasm you can find a fragment shader to work with that produces the following code inside main():

beautiful_color = fancy_varying;
physicsy_properties = props.smoothness;

I suggest modifying the SPIR-V to produce the following instead:

beautiful_color = fancy_varying * (vec4(1) - props.shininess);
physicsy_properties = -props.smoothness / props.shininess;

Here are a few pointers:

• OpConstant is used to create constants,
• OpFNegate can be used to negate floating point scalars and vectors
• OpFSub subtracts floating point scalars and vectors,
• OpFMul multiplies floating point scalars and vectors (per component),
• OpFDiv divides floating point scalars and vectors (per component),

Fancy doing something more complicated? By all means go for it. Here are a couple more pointers to create something even more interesting:

• OpTypeMatrix is used to create matrix types; why not add a matrix field to our buffer object?
• OpMatrixTimesVector and OpVectorTimesMatrix multiply a floating point matrix and a vector,
• OpDot produces the dot product of two floating point vectors,