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Object rotation

To rotate an object in space, use the library function “slRotX, slRotY, slRotZ”. Each controls the rotation corresponding to the coordinate axis at the end of the function name.
Object rotation is achieved by multiplying each vertex coordinate of the object by a transformation matrix called a rotation matrix.

[void slRotX (ANGLE angx);] Add rotation around the X axis to the

object. The rotation angle value is assigned to the parameter.

[void slRotY (ANGLE angy);] Add rotation around the Y axis to the

object. The rotation angle value is assigned to the parameter.

[void slRotZ (ANGLE angz);] Add a rotation around the Z axis to the

object. The rotation angle value is assigned to the parameter.

The following list 4-2 is a program (single-axis rotation) that rotates the square polygon drawn in list 2-1 in Chapter 2 on the Y axis using the library function “slRotY”. The rotation matrix is ​​expressed by the following equation.

List 4-2 sample_4_3_1: Square polygon single-axis rotation routine

Flow 4-2 sample_4_3_1: Square polygon single-axis rotation routine flowchart

List 4-3 below is a program for realizing 2-axis rotation. Rotate the square polygon around the X and Y axes.
The actual operation is the same for single-axis rotation, 2-axis rotation, or 3-axis rotation. By manipulating the angle value of the rotation operation function corresponding to each axis, the object is drawn in a rotated state.

List 4-3 sample_4_3_2: Square polygon biaxial rotation routine

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