3D slice at incorrect position

[zguoch]

Description of the problem

function preset()
{
    figname=Test_3d
    angle_view=-45/25
    width_fig_x=10
    width_fig_y=10
    width_fig_z=7
    # alpha
    alpha_profile=50
    # range
    xmin=0
    xmax=100
    ymin=0
    ymax=50
    zmin=-20
    zmax=0
    xc=`echo $xmin $xmax | awk '{print $1+($2-$1)/2}'`
    yc=`echo $ymin $ymax | awk '{print $1+($2-$1)/2}'`
    zc=`echo $zmin $zmax | awk '{print $1+($2-$1)/2}'`
    len_z=`echo $zmin $zmax | awk '{print ($2-$1)}'`
}
preset

# plot 
gmt begin $figname pdf,png
    gmt basemap -JX$width_fig_x/$width_fig_y -JZ$width_fig_z -R$xmin/$xmax/$ymin/$ymax/$zmin/$zmax -Ba -Bza+l"Z(m)" -BwsenZ+gred  -pz$angle_view/$zmin
    echo "$xc $yc zmin plane" | gmt pstext -JZ -p -F+f20p,Helvetica-Bold,blue=thinner,white+jCM+a190 -Dj0c/0c
    gmt basemap -JX$width_fig_x/$width_fig_y -JZ$width_fig_z -R$xmin/$xmax/$ymin/$ymax/$zmin/$zmax -Bwsenz+ggray  -pz$angle_view/$zmax
    echo "$xc $yc zmax plane" | gmt pstext -JZ -p -F+f20p,Helvetica-Bold,blue=thinner,white+jCM+a190 -Dj0c/0c
    gmt basemap -JX$width_fig_y/$width_fig_z -JZ$width_fig_x -R$ymin/$ymax/$zmin/$zmax/$xmin/$xmax -Ba -BwSenz+glightblue@$alpha_profile -Bx+l"Y(m)" --MAP_FRAME_PEN=1,black@0 --MAP_ANNOT_OFFSET=-0.2   -px$angle_view/$xminn
    echo "$yc $zc ymin plane" | gmt pstext -JZ -p -F+f20p,Helvetica-Bold,blue=thinner,white+jCM+a45 -Dj0c/0c
    gmt basemap -JX$width_fig_x/$width_fig_z -JZ$width_fig_y -R$xmin/$xmax/$zmin/$zmax/$ymin/$ymax -Ba -BwSenz+glightgreen@$alpha_profile -Bx+l"X(m)" --MAP_FRAME_PEN=1,black@0 --MAP_ANNOT_OFFSET=-0.2  -py$angle_view/$ymax
    echo "$xc $zc xminn plane" | gmt pstext -JZ -p -F+f20p,Helvetica-Bold,blue=thinner,white+jCM+a-45 -Dj0c/0c
gmt end
open $figname.pdf
rm tmp* gmt.conf gmt.history 

System information

• Operating system: Mac OS, 10.14.4
• Version of GMT: 6.0.0_c0b3875-dirty

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[zguoch]

I will take time to read the Contributing Guid and Code of Conduct, and will make a "pull request" for this issue. Here I attach the key part of code to solve this issue.

GMT_LOCAL int map_init_three_D (struct GMT_CTRL *GMT) {
//...
//...
if (easy) {
		double xx[4], yy[4];

		xx[0] = xx[3] = GMT->current.proj.rect[XLO]; xx[1] = xx[2] = GMT->current.proj.rect[XHI];
		yy[0] = yy[1] = GMT->current.proj.rect[YLO]; yy[2] = yy[3] = GMT->current.proj.rect[YHI];
		// which plane in 3d projection
		int plane = GMT->current.proj.z_project.view_plane;
		// the offset coefficenece of transformation matrix: e and e should be keep consistent with the case of GMT_Z
		switch (plane % 3) {
			case GMT_X:
				// -Rymin/ymax/zmin/zmax/xmin/xmax
				xx[0] = xx[3] = GMT->current.proj.zmin; xx[1] = xx[2] = GMT->current.proj.zmax;
				yy[0] = yy[1] = GMT->current.proj.rect[XLO]; yy[2] = yy[3] = GMT->current.proj.rect[XHI];
				break;
			case GMT_Y:
				// -Rxmin/xmax/zmin/zmax/ymin/ymax
				xx[0] = xx[3] = GMT->current.proj.rect[XLO]; xx[1] = xx[2] = GMT->current.proj.rect[XHI];
				yy[0] = yy[1] = GMT->current.proj.zmin; yy[2] = yy[3] = GMT->current.proj.zmax;
				break;
			case GMT_Z:
				// -Rxmin/xmax/ymin/ymax/zmin/zmax
				xx[0] = xx[3] = GMT->current.proj.rect[XLO]; xx[1] = xx[2] = GMT->current.proj.rect[XHI];
				yy[0] = yy[1] = GMT->current.proj.rect[YLO]; yy[2] = yy[3] = GMT->current.proj.rect[YHI];
				break;
		}
		for (i = 0; i < 4; i++) {
			gmt_xy_to_geo (GMT, &GMT->current.proj.z_project.corner_x[i], &GMT->current.proj.z_project.corner_y[i], xx[i], yy[i]);
			gmt_xyz_to_xy (GMT, xx[i], yy[i], gmt_z_to_zz(GMT, GMT->common.R.wesn[ZLO]), &x, &y);
			GMT->current.proj.z_project.xmin = MIN (GMT->current.proj.z_project.xmin, x);
			GMT->current.proj.z_project.xmax = MAX (GMT->current.proj.z_project.xmax, x);
			GMT->current.proj.z_project.ymin = MIN (GMT->current.proj.z_project.ymin, y);
			GMT->current.proj.z_project.ymax = MAX (GMT->current.proj.z_project.ymax, y);
			gmt_xyz_to_xy (GMT, xx[i], yy[i], gmt_z_to_zz(GMT, GMT->common.R.wesn[ZHI]), &x, &y);
			GMT->current.proj.z_project.xmin = MIN (GMT->current.proj.z_project.xmin, x);
			GMT->current.proj.z_project.xmax = MAX (GMT->current.proj.z_project.xmax, x);
			GMT->current.proj.z_project.ymin = MIN (GMT->current.proj.z_project.ymin, y);
			GMT->current.proj.z_project.ymax = MAX (GMT->current.proj.z_project.ymax, y);
		}
	}
//...
}

[PaulWessel]

What you say, @remkos ?

[remkos]

This looks like a duplicate of issue #529.
I'll put it on me to implement and test the code by @CosmicScholar
Thank you for your contribution!

[joa-quim]

It's a complicated test (for me) to reproduce. Is it still buggy (there changes in this regard) or can we close it?

[PaulWessel]

This problem seems to have taken a turn for the worse. Running it today I get