Added and documented the "exposed" render mode primitive.

CONTRIBUTORS.rst

@@ -69,6 +69,7 @@ feature.
  * Ryan McCue <ryanmccue@cubegames.net>
  * Zach McCullough <nosrepa@gmail.com>
  * Mike <mike@snowcrash.ca>
+ * Adam Novak <interfect@gmail.com>
  * Morlok8k <otis.spankmeyer@gmail.com>
  * Richard Pastrick <rpastric@contre.us>
  * Ryan Rector <rmrector@gmail.com>

docs/config.rst

@@ -611,6 +611,14 @@ Depth
     max
         highest level of blocks to render. Default: 255
 
+Exposed
+    Only renders blocks that are exposed (adjacent to a transparent block).
+    
+    **Options**
+    
+    mode
+        when set to 1, inverts the render mode, only drawing unexposed blocks. Default: 0
+
 EdgeLines
     Draw edge lines on the back side of blocks, to help distinguish them from
     the background.

overviewer_core/rendermodes.py

@@ -62,6 +62,12 @@ class Depth(RenderPrimitive):
         "min": ("lowest level of blocks to render", 0),
         "max": ("highest level of blocks to render", 255),
     }
+    
+class Exposed(RenderPrimitive):
+    name = "exposed"
+    options = {
+        "mode": ("0 = exposed blocks only, 1 = unexposed blocks only", 0),
+    }
 
 class EdgeLines(RenderPrimitive):
     name = "edge-lines"

overviewer_core/src/primitives/exposed.c

@@ -0,0 +1,91 @@
+/* 
+ * This file is part of the Minecraft Overviewer.
+ *
+ * Minecraft Overviewer is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Minecraft Overviewer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with the Overviewer.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "../overviewer.h"
+
+typedef struct {
+    unsigned int mode; /* 0 = exposed only, 1 = unexposed only */
+} PrimitiveExposed;
+
+static int
+exposed_start(void *data, RenderState *state, PyObject *support) {
+    PrimitiveExposed *self = (PrimitiveExposed *)data;
+    
+    if (!render_mode_parse_option(support, "mode", "I", &(self->mode)))
+        return 1;
+        
+    return 0;
+}
+
+static int
+exposed_hidden(void *data, RenderState *state, int x, int y, int z) {
+    PrimitiveExposed *self = (PrimitiveExposed *)data;
+    
+    /* Unset these flags if seeming exposure from any of these directions would
+     * be due to not having data there.
+     */
+    int validMinusX = 1;
+    int validPlusY = 1;
+    int validPlusZ = 1;
+
+    /* special handling for section boundaries */
+    /* If the neighboring section has no block data, ignore exposure from that
+     * direction 
+     */
+    if (x == 0 && (!(state->chunks[0][1].loaded) || state->chunks[0][1].sections[state->chunky].blocks == NULL)) {
+        /* No data in -x direction */
+        validMinusX = 0;
+    }
+        
+    if (y == 15 && (state->chunky + 1 >= SECTIONS_PER_CHUNK || state->chunks[1][1].sections[state->chunky + 1].blocks == NULL)) {
+        /* No data in +y direction */
+        validPlusY = 0;
+    }
+    
+    if (z == 15 && (!(state->chunks[1][2].loaded) || state->chunks[1][2].sections[state->chunky].blocks == NULL)) {
+        /* No data in +z direction */
+        validPlusZ = 0;
+    }
+    
+    /* If any of the 6 blocks adjacent to us are transparent, we're exposed */
+    if( (validMinusX && is_transparent(get_data(state, BLOCKS, x-1, y, z))) ||
+        is_transparent(get_data(state, BLOCKS, x+1, y, z)) ||
+        is_transparent(get_data(state, BLOCKS, x, y-1, z)) ||
+        (validPlusY && is_transparent(get_data(state, BLOCKS, x, y+1, z))) ||
+        is_transparent(get_data(state, BLOCKS, x, y, z-1)) ||
+        (validPlusZ && is_transparent(get_data(state, BLOCKS, x, y, z+1 ))) ) {
+    
+        /* Block is exposed */
+        /* Returns 1 and hides us if we're rendering unexposed blocks, 0 and 
+         * shows us if we're rendering exposed blocks 
+         */
+        return self->mode; 
+    
+    }
+    
+    /* We have no valid evidence that the block is exposed */ 
+    return !(self->mode); /* Hide in normal mode, reveal in inverted mode */
+}
+
+RenderPrimitiveInterface primitive_exposed = {
+    "exposed", sizeof(PrimitiveExposed),
+    exposed_start,
+    NULL,
+    NULL,
+    exposed_hidden,
+    NULL,
+};