first ideas for placing oriented blocks

diff --git a/src/ui/ui.cpp b/src/ui/ui.cpp
index 5f60d4401d056e116422b72941965217cd26edce..89c34109be2340b9214a6f3e8854cddb49672b06 100644 (file)
--- a/src/ui/ui.cpp
+++ b/src/ui/ui.cpp
@@ -29,6 +29,7 @@
 #include <map>
 #include <sstream>
 #include <glm/gtc/matrix_transform.hpp>
+#include <glm/gtx/projection.hpp>
 #include <glm/gtx/rotate_vector.hpp>
 #include <glm/gtx/io.hpp>
 
@@ -182,14 +183,59 @@ void DirectInput::PickBlock() {
 }
 
 void DirectInput::PlaceBlock() {
+       // update block focus
        UpdatePlayer();
+       // do nothing if not looking at any block
        if (!BlockFocus()) return;
 
+       // determine block adjacent to the face the player is looking at
        BlockLookup next_block(BlockFocus().chunk, BlockFocus().BlockPos(), Block::NormalFace(BlockFocus().normal));
+       // abort if it's unavailable
        if (!next_block) {
                return;
        }
-       manip.SetBlock(next_block.GetChunk(), next_block.GetBlockIndex(), Block(InventorySlot() + 1));
+
+       // "can replace" check
+       // this prevents players from replacing solid blocks e.g. by looking through slabs
+       // simple for now, should be expanded to include things like
+       // entities in the way or replacable blocks like water and stuff
+       if (next_block.GetBlock().type != 0) {
+               return;
+       }
+
+       Block new_block(InventorySlot() + 1);
+
+       // block's up vector
+       // align with player's up
+       const glm::vec3 player_up(GetPlayer().GetEntity().Up());
+       new_block.SetFace(Block::NormalFace(player_up));
+       // to align with player's local up/down look (like stairs in minecraft), just invert
+       // it if pitch is positive
+       // or, align with focus normal (like logs in minecraft)
+
+       // determine block's turn (local rotation about up axis)
+       // when aligned with player's up (first mode, and currently the only one implemented)
+       // project the player's view forward onto his entity's XZ plane and
+       // use the closest cardinal direction it's pointing in
+       const glm::vec3 view_forward(-GetPlayer().GetEntity().ViewTransform(GetPlayer().GetEntity().ChunkCoords())[3]);
+       // if view is straight up or down, this will be a null vector (NaN after normalization)
+       // in that case maybe the model forward should be used?
+       // the current implementation implicitly falls back to TURN_NONE which is -Z
+       const glm::vec3 local_forward(normalize(view_forward - proj(view_forward, player_up)));
+       // FIXME: I suspect this only works when player_up is positive Y
+       if (local_forward.x > 0.707f) {
+               new_block.SetTurn(Block::TURN_RIGHT);
+       } else if (local_forward.z > 0.707f) {
+               new_block.SetTurn(Block::TURN_AROUND);
+       } else if (local_forward.x < -0.707f) {
+               new_block.SetTurn(Block::TURN_LEFT);
+       }
+       // for mode two ("minecraft stairs") it should work the same, but I haven't properly
+       // thought that through (well, that's also true about the whole face/turn thing, but oh well)
+       // mode three I have absoloutely no clue. that placement would be appropriate for pipe-like
+       // blocks, where turn shouldn't make a difference, but what if it does?
+
+       manip.SetBlock(next_block.GetChunk(), next_block.GetBlockIndex(), new_block);
        Invalidate();
 }
 

diff --git a/src/world/Entity.hpp b/src/world/Entity.hpp
index e38e0b449e79bf41eae31c4800a7bc10ad04d6ea..b140a08d95d7b21db850ef1966f841ffccf938f3 100644 (file)
--- a/src/world/Entity.hpp
+++ b/src/world/Entity.hpp
@@ -96,6 +96,8 @@ public:
 
        /// get a transform for this entity's coordinate space
        const glm::mat4 &Transform() const noexcept { return model_transform; }
+       /// get the entity's local up vector
+       const glm::vec4 &Up() const noexcept { return model_transform[1]; }
        /// get a transform for this entity's coordinate space relative to reference chunk
        glm::mat4 Transform(const glm::ivec3 &reference) const noexcept;
        /// get a transform for this entity's view space relative to reference chunk