Add disable_if_always_disabled() to Block objects.

[nageru] / nageru / scene.cpp

diff --git a/nageru/scene.cpp b/nageru/scene.cpp
index 2612de639961e8336d3eb4a6a8d8f8fb1f5f842a..70bccbe1a73f11d31424654a630ef2d1600e21db 100644 (file)
--- a/nageru/scene.cpp
+++ b/nageru/scene.cpp
@@ -59,9 +59,9 @@ size_t Scene::compute_chain_number_for_block(size_t block_idx, const bitset<256>
 
        size_t currently_chosen_alternative;
        if (disabled.test(block_idx)) {
-               // It doesn't matter, so pick 0 as the canonical choice
+               // It doesn't matter, so pick the canonical choice
                // (this is the only one that is actually instantiated).
-               currently_chosen_alternative = 0;
+               currently_chosen_alternative = block->canonical_alternative;
        } else {
                currently_chosen_alternative = block->currently_chosen_alternative;
        }
@@ -80,8 +80,27 @@ bitset<256> Scene::find_disabled_blocks(size_t chain_idx) const
 {
        assert(blocks.size() < 256);
 
-       bitset<256> ret;
-       find_disabled_blocks(chain_idx, blocks.size() - 1, /*currently_disabled=*/false, &ret);
+       // The find_disabled_blocks() recursion logic needs only one pass by itself,
+       // but the disabler logic is not so smart, so we just run multiple times
+       // until it converges.
+       bitset<256> prev, ret;
+       do {
+               find_disabled_blocks(chain_idx, blocks.size() - 1, /*currently_disabled=*/false, &ret);
+               prev = ret;
+               for (Block *block : blocks) {
+                       EffectType chosen_type = block->alternatives[block->chosen_alternative(chain_idx)]->effect_type;
+                       if (ret.test(block->idx) || chosen_type == IDENTITY_EFFECT) continue;  // Already disabled.
+
+                       for (Block::Index disabler_idx : block->disablers) {
+                               Block *disabler = blocks[disabler_idx];
+                               EffectType chosen_type = disabler->alternatives[disabler->chosen_alternative(chain_idx)]->effect_type;
+                               if (ret.test(disabler->idx) || chosen_type == IDENTITY_EFFECT) {
+                                       ret.set(block->idx);
+                                       break;
+                               }
+                       }
+               }
+       } while (prev != ret);
        return ret;
 }
 
@@ -113,7 +132,8 @@ bool Scene::is_noncanonical_chain(size_t chain_idx) const
        }
        assert(blocks.size() < 256);
        for (size_t block_idx = 0; block_idx < blocks.size(); ++block_idx) {
-               if (disabled.test(block_idx) && blocks[block_idx]->chosen_alternative(chain_idx) != 0) {
+               Block *block = blocks[block_idx];
+               if (disabled.test(block_idx) && block->chosen_alternative(chain_idx) != block->canonical_alternative) {
                        return true;
                }
        }
@@ -217,6 +237,15 @@ int Scene::add_effect(lua_State* L)
                block->alternatives.push_back(blueprint);
        }
 
+       int identity_index = find_index_of(block, IDENTITY_EFFECT);
+       if (identity_index == -1) {
+               block->canonical_alternative = 0;
+       } else {
+               // Pick the IdentityEffect as the canonical alternative, in case it
+               // helps us disable more stuff.
+               block->canonical_alternative = identity_index;
+       }
+
        find_inputs_for_block(L, scene, block);
        scene->blocks.push_back(block);
 
@@ -237,6 +266,8 @@ int Scene::add_optional_effect(lua_State* L)
        // An IdentityEffect will be the alternative for when the effect is disabled.
        block->alternatives.push_back(new EffectBlueprint(IDENTITY_EFFECT));
 
+       block->canonical_alternative = 1;
+
        find_inputs_for_block(L, scene, block);
        scene->blocks.push_back(block);
 
@@ -633,6 +664,27 @@ int Block_disable(lua_State *L)
        return 0;
 }
 
+int Block_always_disable_if_disabled(lua_State *L)
+{
+       assert(lua_gettop(L) == 2);
+       Block *block = *(Block **)luaL_checkudata(L, 1, "Block");
+       Block *disabler_block = *(Block **)luaL_checkudata(L, 2, "Block");
+
+       int my_alternative = find_index_of(block, IDENTITY_EFFECT);
+       int their_alternative = find_index_of(disabler_block, IDENTITY_EFFECT);
+       if (my_alternative == -1) {
+               luaL_error(L, "always_disable_if_disabled() called on something that didn't have an IdentityEffect fallback (try add_optional_effect())");
+       }
+       if (their_alternative == -1) {
+               luaL_error(L, "always_disable_if_disabled() with an argument that didn't have an IdentityEffect fallback (try add_optional_effect())");
+       }
+
+       block->disablers.push_back(disabler_block->idx);
+
+       lua_pop(L, 2);
+       return 0;
+}
+
 int Block_set_int(lua_State *L)
 {
        assert(lua_gettop(L) == 3);