Add RenderPrimitive opposite to hide (show)

docs/config.rst

@@ -1141,6 +1141,15 @@ Hide
     blocks
         A list of block ids, or (blockid, data) tuples to hide.
 
+Show
+    Show blocks based on blockid. Blocks hidden in this way will be
+    trated exactly the same as air.
+
+    **Options**
+
+    blocks
+        A list of block ids, or (blockid, data) tuples to show.
+
 DepthTinting
     Tint blocks a color according to their depth (height) from bedrock. Useful
     mainly for cave renders.

overviewer_core/rendermodes.py

@@ -237,6 +237,12 @@ class Hide(RenderPrimitive):
         'blocks' : ('a list of blockids or (blockid, data) tuples of blocks to hide', []),
     }
 
+class Show(RenderPrimitive):
+    name = "show"
+    options = {
+        'blocks': ('a list of blockids or (blockid, data) tuples of blocks to show', []),
+    }
+
 # Built-in rendermodes for your convenience!
 normal = [Base(), EdgeLines()]
 lighting = [Base(), EdgeLines(), Lighting()]

overviewer_core/src/primitives/show.c

@@ -0,0 +1,118 @@
+/*
+ * 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 "../mc_id.h"
+#include "../overviewer.h"
+
+struct ShowRule {
+    mc_block_t blockid;
+    bool has_data;
+    uint8_t data;
+};
+
+typedef struct {
+    struct ShowRule* rules;
+} RenderPrimitiveShow;
+
+static bool
+show_start(void* data, RenderState* state, PyObject* support) {
+    PyObject* opt;
+    RenderPrimitiveShow* self = (RenderPrimitiveShow*)data;
+    self->rules = NULL;
+
+    if (!render_mode_parse_option(support, "blocks", "O", &(opt)))
+        return true;
+    if (opt && opt != Py_None) {
+        Py_ssize_t blocks_size = 0, i;
+
+        if (!PyList_Check(opt)) {
+            PyErr_SetString(PyExc_TypeError, "'blocks' must be a list");
+            return true;
+        }
+
+        blocks_size = PyList_GET_SIZE(opt);
+        self->rules = calloc(blocks_size + 1, sizeof(struct ShowRule));
+        if (self->rules == NULL) {
+            return true;
+        }
+
+        for (i = 0; i < blocks_size; i++) {
+            PyObject* block = PyList_GET_ITEM(opt, i);
+
+            if (PyLong_Check(block)) {
+                /* format 1: just a block id */
+                self->rules[i].blockid = PyLong_AsLong(block);
+                self->rules[i].has_data = false;
+            } else if (PyArg_ParseTuple(block, "Hb", &(self->rules[i].blockid), &(self->rules[i].data))) {
+                /* format 2: (blockid, data) */
+                self->rules[i].has_data = true;
+            } else {
+                /* format not recognized */
+                free(self->rules);
+                self->rules = NULL;
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+static void
+show_finish(void* data, RenderState* state) {
+    RenderPrimitiveShow* self = (RenderPrimitiveShow*)data;
+
+    if (self->rules) {
+        free(self->rules);
+    }
+}
+
+static bool
+show_hidden(void* data, RenderState* state, int32_t x, int32_t y, int32_t z) {
+    RenderPrimitiveShow* self = (RenderPrimitiveShow*)data;
+    uint32_t i;
+    mc_block_t block;
+
+    if (self->rules == NULL)
+        return true;
+
+    block = get_data(state, BLOCKS, x, y, z);
+    for (i = 0; self->rules[i].blockid != block_air; i++) {
+        if (block == self->rules[i].blockid) {
+            uint8_t data;
+
+            if (!(self->rules[i].has_data))
+                return false;
+
+            data = get_data(state, DATA, x, y, z);
+            if (data == self->rules[i].data)
+                return false;
+        }
+    }
+
+    return true;
+}
+
+RenderPrimitiveInterface primitive_show = {
+    "show",
+    sizeof(RenderPrimitiveShow),
+    show_start,
+    show_finish,
+    NULL,
+    show_hidden,
+    NULL,
+};