Fix clipping plane issues

The clipping plane is flat, so the distance between the camera and the
clipping plane varies based on where screen location. I.e. it is closest
in the center and farther at the corners. Add a offset to elev to
account of this. It would be better to use a sin or to calculate
distances directly, but this is easy and appears to work.

diff --git a/src/grits-opengl.c b/src/grits-opengl.c
index dc13ea2411bbdcb6eb482b1efb95032b4a1064cd..323e7f34b67e2d03dfc57aab84fe2a05d84309dc 100644 (file)
--- a/src/grits-opengl.c
+++ b/src/grits-opengl.c
@@ -69,8 +69,8 @@ static void _set_visuals(GritsOpenGL *opengl)
        double height = GTK_WIDGET(opengl)->allocation.height;
        double ang    = atan(height/FOV_DIST);
        double atmos  = 100000;
-       double near   = MAX(elev - atmos, 10);    // View 100km of atmosphere
-       double far    = elev + 2*EARTH_R + atmos; // on both sides of the earth
+       double near   = MAX(elev*0.75 - atmos, 50); // View 100km of atmosphere
+       double far    = elev + 2*EARTH_R + atmos;   // on both sides of the earth
 
        grits_viewer_get_location(GRITS_VIEWER(opengl), &lat, &lon, &elev);
        glViewport(0, 0, width, height);