Hi Aaron,
The behaviour arises because of the "axis equal" command. When you use the "axis equal" command, it adjusts the plot to ensure equal scaling on all axes. This command checks the current position and limits of the axes, calculates the "PlotBoxAspectRaio" (by setting it to "auto"), then sets the limits to be auto in the unconstrained dimension. Because the math it uses is transient, applying "axis equal" before setting the final view of the plot, means that the the calculated values are outdated and irrelevant.
One can visualize the behavior of axis equal as effectively adjusting the limits in one dimension to satisfy the (current) aspect ratio constraints.
Thus, if you call "axis equal" after setting the "View", you'll find the corresponding lines to be parallel
f = figure('Color', 'w'); % Figure window
% Coordinates of drawn object
ax1 = [-1.0, +1.0, NaN, 0.0, 0.0, NaN, 0.0, 0.0;
0.0, 0.0, NaN, -1.0, +1.0, NaN, 0.0, 0.0;
0.0, 0.0, NaN, 0.0, 0.0, NaN, -1.0, +1.0];
ax2 = [-2.0, +2.0, NaN, 0.0, 0.0, NaN, 0.0, 0.0;
0.0, 0.0, NaN, -1.0, +1.0, NaN, 0.0, 0.0;
0.0, 0.0, NaN, 0.0, 0.0, NaN, -1.0, +1.0];
% Axes 1
a1 = axes(f, 'Units', 'normalized', 'OuterPosition', [0.0,0.0,0.5,1.0]);
plot3(ax1(1,:),ax1(2,:),ax1(3,:), 'k', 'LineWidth', 1.0)
rotate3d on
% Axes 2
a2 = axes(f, 'Units', 'normalized', 'OuterPosition', [0.5,0.0,0.5,1.0]);
plot3(ax2(1,:),ax2(2,:),ax2(3,:), 'k', 'LineWidth', 1.0)
rotate3d on
% Link view property
link = linkprop([a1,a2],'View');
set([a1,a2], "View", [45,90]);
axis(a1, 'equal', 'vis3d', 'off');
axis(a2, 'equal', 'vis3d', 'off');
