glm stuff

CMakeLists.txt

@@ -78,6 +78,7 @@ find_package(CLI11 CONFIG REQUIRED)
 find_package(rapidjson CONFIG REQUIRED)
 find_package(assimp CONFIG REQUIRED)
 find_package(Bullet CONFIG REQUIRED)
+find_package(glm CONFIG REQUIRED)
 
 if(BUILD_SDL3_APP)
 add_executable(sdl3_app
@@ -94,7 +95,7 @@ add_executable(sdl3_app
         src/script/cube_script.cpp
     )
     target_include_directories(sdl3_app PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/src")
-    target_link_libraries(sdl3_app PRIVATE sdl::sdl Vulkan::Vulkan lua::lua CLI11::CLI11 rapidjson assimp::assimp Bullet::Bullet)
+    target_link_libraries(sdl3_app PRIVATE sdl::sdl Vulkan::Vulkan lua::lua CLI11::CLI11 rapidjson assimp::assimp Bullet::Bullet glm::glm)
     target_compile_definitions(sdl3_app PRIVATE SDL_MAIN_HANDLED)
 
     file(COPY "${CMAKE_CURRENT_SOURCE_DIR}/shaders" DESTINATION "${CMAKE_CURRENT_BINARY_DIR}")
@@ -108,5 +109,5 @@ add_executable(cube_script_tests
     src/script/cube_script.cpp
 )
 target_include_directories(cube_script_tests PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/src")
-target_link_libraries(cube_script_tests PRIVATE lua::lua assimp::assimp Bullet::Bullet)
+target_link_libraries(cube_script_tests PRIVATE lua::lua assimp::assimp Bullet::Bullet glm::glm)
 add_test(NAME cube_script_tests COMMAND cube_script_tests)

scripts/cube_logic.lua

@@ -122,25 +122,6 @@ local cube_state = {
 }
 local physics_last_time = 0.0
 
-local function quaternion_to_matrix(q)
-    local x, y, z, w = q[1], q[2], q[3], q[4]
-    local xx = x * x
-    local yy = y * y
-    local zz = z * z
-    local xy = x * y
-    local xz = x * z
-    local yz = y * z
-    local wx = w * x
-    local wy = w * y
-    local wz = w * z
-    return {
-        1.0 - 2.0 * yy - 2.0 * zz, 2.0 * xy + 2.0 * wz,     2.0 * xz - 2.0 * wy,     0.0,
-        2.0 * xy - 2.0 * wz,     1.0 - 2.0 * xx - 2.0 * zz, 2.0 * yz + 2.0 * wx,     0.0,
-        2.0 * xz + 2.0 * wy,     2.0 * yz - 2.0 * wx,     1.0 - 2.0 * xx - 2.0 * yy, 0.0,
-        0.0,                     0.0,                     0.0,                     1.0,
-    }
-end
-
 local function initialize_physics()
     if type(physics_create_box) ~= "function" then
         error("physics_create_box() is unavailable")
@@ -269,13 +250,7 @@ end
 local function create_physics_cube(shader_key)
     local function compute_model_matrix(time)
         sync_physics(time)
-        local offset = math3d.translation(
-            cube_state.position[1],
-            cube_state.position[2],
-            cube_state.position[3]
-        )
-        local rotation_matrix = quaternion_to_matrix(cube_state.rotation)
-        return math3d.multiply(offset, rotation_matrix)
+        return glm_matrix_from_transform(cube_state.position, cube_state.rotation)
     end
 
     return {

src/script/cube_script.cpp

@@ -5,6 +5,10 @@
 #include <assimp/postprocess.h>
 #include <assimp/scene.h>
 #include <btBulletDynamicsCommon.h>
+#include <glm/glm.hpp>
+#include <glm/gtc/matrix_transform.hpp>
+#include <glm/gtc/quaternion.hpp>
+#include <glm/gtc/type_ptr.hpp>
 
 #include <array>
 #include <cstring>
@@ -220,6 +224,24 @@ bool TryLoadMeshPayload(const CubeScript* script,
     return true;
 }
 
+glm::vec3 ToVec3(const std::array<float, 3>& value) {
+    return glm::vec3(value[0], value[1], value[2]);
+}
+
+glm::quat ToQuat(const std::array<float, 4>& value) {
+    // Lua exposes {x, y, z, w}
+    return glm::quat(value[3], value[0], value[1], value[2]);
+}
+
+void PushMatrix(lua_State* L, const glm::mat4& matrix) {
+    lua_newtable(L);
+    const float* ptr = glm::value_ptr(matrix);
+    for (int i = 0; i < 16; ++i) {
+        lua_pushnumber(L, ptr[i]);
+        lua_rawseti(L, -2, i + 1);
+    }
+}
+
 int PushMeshToLua(lua_State* L, const MeshPayload& payload) {
     lua_newtable(L); // mesh
 
@@ -347,6 +369,16 @@ int LuaPhysicsGetTransform(lua_State* L) {
     return 1;
 }
 
+int LuaGlmMatrixFromTransform(lua_State* L) {
+    std::array<float, 3> translation = CubeScript::ReadVector3(L, 1);
+    std::array<float, 4> rotation = CubeScript::ReadQuaternion(L, 2);
+    glm::vec3 pos = ToVec3(translation);
+    glm::quat quat = ToQuat(rotation);
+    glm::mat4 matrix = glm::translate(glm::mat4(1.0f), pos) * glm::mat4_cast(quat);
+    PushMatrix(L, matrix);
+    return 1;
+}
+
 std::array<float, 16> IdentityMatrix() {
     return {1.0f, 0.0f, 0.0f, 0.0f,
             0.0f, 1.0f, 0.0f, 0.0f,
@@ -378,8 +410,8 @@ CubeScript::CubeScript(const std::filesystem::path& scriptPath, bool debugEnable
     lua_pushcclosure(L_, &LuaPhysicsGetTransform, 1);
     lua_setglobal(L_, "physics_get_transform");
     lua_pushlightuserdata(L_, this);
-    lua_pushcclosure(L_, &LuaLoadMeshFromFile, 1);
-    lua_setglobal(L_, "load_mesh_from_file");
+    lua_pushcclosure(L_, &LuaGlmMatrixFromTransform, 1);
+    lua_setglobal(L_, "glm_matrix_from_transform");
     lua_pushboolean(L_, debugEnabled_);
     lua_setglobal(L_, "lua_debug");
     auto scriptDir = scriptPath.parent_path();