fixed off-by-one error: left seam is always correctly specified now

dkogan · Nov 25, 2013 · df90ace · df90ace
1 parent c07bd4d
commit df90ace
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Showing 2 changed files with 2 additions and 2 deletions.
diff --git a/render_terrain.c b/render_terrain.c
@@ -310,7 +310,7 @@ static bool loadGeometry( float view_lat, float view_lon,
 
         // left side; negative to indicate that this is a duplicate for the left seam
         vertices[vertex_buf_idx++] = view_i;
-        vertices[vertex_buf_idx++] = -j;
+        vertices[vertex_buf_idx++] = -(j+1); // extra 1 because I can't assume that -0 < 0
         vertices[vertex_buf_idx++] = sampleDEM(view_i_DEMcoords, j_dem,
                                                dems[baseDEMfileE - renderStartDEMfileE][DEMfileN - renderStartDEMfileN]);
 

diff --git a/vertex.glsl b/vertex.glsl
@@ -35,7 +35,7 @@ void main(void)
   }
   else if( vin.y < 0.0 )
   {
-    vin.y *= -1.0;
+    vin.y = -vin.y - 1.0; // extra 1 because I can't assume that -0 < 0
     at_right_seam = true;
   }