Rotation

src/dusk/engine/engine.c

@@ -23,14 +23,16 @@
 
 engine_t ENGINE;
 texture_t TEXTURE;
-#pragma pack(push, 1)
 color_t TEXTURE_COLORS[] = {
   COLOR_RED, COLOR_GREEN, COLOR_MAGENTA, COLOR_CYAN,
   COLOR_BLUE, COLOR_WHITE, COLOR_YELLOW, COLOR_BLACK,
   COLOR_CYAN, COLOR_MAGENTA, COLOR_GREEN, COLOR_RED,
   COLOR_WHITE, COLOR_BLUE, COLOR_BLACK, COLOR_YELLOW
 };
-#pragma pack(pop)
+entityid_t ent1;
+componentid_t ent1Pos;
+componentid_t ent1Mesh;
+componentid_t ent1Mat;
 
 errorret_t engineInit(const int32_t argc, const char_t **argv) {
   memoryZero(&ENGINE, sizeof(engine_t));
@@ -62,10 +64,10 @@ errorret_t engineInit(const int32_t argc, const char_t **argv) {
   );
   componentid_t camCam = entityAddComponent(cam, COMPONENT_TYPE_CAMERA);
 
-  entityid_t ent1 = entityManagerAdd();
+  ent1 = entityManagerAdd();
-  componentid_t ent1Pos = entityAddComponent(ent1, COMPONENT_TYPE_POSITION);
+  ent1Pos = entityAddComponent(ent1, COMPONENT_TYPE_POSITION);
-  componentid_t ent1Mesh = entityAddComponent(ent1, COMPONENT_TYPE_MESH);
+  ent1Mesh = entityAddComponent(ent1, COMPONENT_TYPE_MESH);
-  componentid_t ent1Mat = entityAddComponent(ent1, COMPONENT_TYPE_MATERIAL);
+  ent1Mat = entityAddComponent(ent1, COMPONENT_TYPE_MATERIAL);
 
   textureInit(&TEXTURE, 4, 4, TEXTURE_FORMAT_RGBA, (texturedata_t){
     .rgbaColors = TEXTURE_COLORS
@@ -80,8 +82,7 @@ errorret_t engineInit(const int32_t argc, const char_t **argv) {
   ));
 
   shadermaterial_t *mat = entityMaterialGetShaderMaterial(ent1, ent1Mat);
-  // mat->unlit.color = COLOR_WHITE;
+  mat->unlit.color = COLOR_WHITE;
-  mat->unlit.color = COLOR_RED;
   mat->unlit.texture = &TEXTURE;
 
   // EOF
@@ -99,6 +100,11 @@ errorret_t engineUpdate(void) {
   timeUpdate();
   inputUpdate();
 
+  vec3 rotation;
+  entityPositionGetRotation(ent1, ent1Pos, rotation);
+  rotation[1] += 0.01f;
+  entityPositionSetRotation(ent1, ent1Pos, rotation);
+
   uiUpdate();
   errorChain(sceneUpdate());
   errorChain(gameUpdate());

src/dusk/entity/component/display/entityposition.c

@@ -15,6 +15,9 @@ void entityPositionInit(
     entityId, componentId, COMPONENT_TYPE_POSITION
   );
 
+  glm_vec3_zero(pos->position);
+  glm_vec3_zero(pos->rotation);
+  glm_vec3_one(pos->scale);
   glm_mat4_identity(pos->transform);
 }
 
@@ -29,6 +32,7 @@ void entityPositionLookAt(
     entityId, componentId, COMPONENT_TYPE_POSITION
   );
   glm_lookat(eye, target, up, pos->transform);
+  entityPositionDecompose(pos);
 }
 
 void entityPositionGetTransform(
@@ -41,3 +45,140 @@ void entityPositionGetTransform(
   );
   glm_mat4_copy(pos->transform, dest);
 }
+
+void entityPositionGetPosition(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 dest
+) {
+  entityposition_t *pos = componentGetData(
+    entityId, componentId, COMPONENT_TYPE_POSITION
+  );
+  glm_vec3_copy(pos->position, dest);
+}
+
+void entityPositionSetPosition(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 position
+) {
+  entityposition_t *pos = componentGetData(
+    entityId, componentId, COMPONENT_TYPE_POSITION
+  );
+  glm_vec3_copy(position, pos->position);
+  entityPositionRebuild(pos);
+}
+
+void entityPositionGetRotation(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 dest
+) {
+  entityposition_t *pos = componentGetData(
+    entityId, componentId, COMPONENT_TYPE_POSITION
+  );
+  glm_vec3_copy(pos->rotation, dest);
+}
+
+void entityPositionSetRotation(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 rotation
+) {
+  entityposition_t *pos = componentGetData(
+    entityId, componentId, COMPONENT_TYPE_POSITION
+  );
+  glm_vec3_copy(rotation, pos->rotation);
+  entityPositionRebuild(pos);
+}
+
+void entityPositionGetScale(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 dest
+) {
+  entityposition_t *pos = componentGetData(
+    entityId, componentId, COMPONENT_TYPE_POSITION
+  );
+  glm_vec3_copy(pos->scale, dest);
+}
+
+void entityPositionSetScale(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 scale
+) {
+  entityposition_t *pos = componentGetData(
+    entityId, componentId, COMPONENT_TYPE_POSITION
+  );
+  glm_vec3_copy(scale, pos->scale);
+  entityPositionRebuild(pos);
+}
+
+void entityPositionRebuild(entityposition_t *pos) {
+  glm_mat4_identity(pos->transform);
+  glm_translate(pos->transform, pos->position);
+  glm_rotate_x(pos->transform, pos->rotation[0], pos->transform);
+  glm_rotate_y(pos->transform, pos->rotation[1], pos->transform);
+  glm_rotate_z(pos->transform, pos->rotation[2], pos->transform);
+  glm_scale(pos->transform, pos->scale);
+}
+
+void entityPositionDecompose(entityposition_t *pos) {
+  // Translation: column 3
+  pos->position[0] = pos->transform[3][0];
+  pos->position[1] = pos->transform[3][1];
+  pos->position[2] = pos->transform[3][2];
+
+  // Scale: length of each basis column (xyz only)
+  pos->scale[0] = sqrtf(
+    pos->transform[0][0] * pos->transform[0][0] +
+    pos->transform[0][1] * pos->transform[0][1] +
+    pos->transform[0][2] * pos->transform[0][2]
+  );
+  pos->scale[1] = sqrtf(
+    pos->transform[1][0] * pos->transform[1][0] +
+    pos->transform[1][1] * pos->transform[1][1] +
+    pos->transform[1][2] * pos->transform[1][2]
+  );
+  pos->scale[2] = sqrtf(
+    pos->transform[2][0] * pos->transform[2][0] +
+    pos->transform[2][1] * pos->transform[2][1] +
+    pos->transform[2][2] * pos->transform[2][2]
+  );
+
+  // Normalize columns to isolate the rotation matrix
+  float invS0 = pos->scale[0] > 0.0f ? 1.0f / pos->scale[0] : 0.0f;
+  float invS1 = pos->scale[1] > 0.0f ? 1.0f / pos->scale[1] : 0.0f;
+  float invS2 = pos->scale[2] > 0.0f ? 1.0f / pos->scale[2] : 0.0f;
+
+  mat4 r;
+  glm_mat4_identity(r);
+  r[0][0] = pos->transform[0][0] * invS0;
+  r[0][1] = pos->transform[0][1] * invS0;
+  r[0][2] = pos->transform[0][2] * invS0;
+  r[1][0] = pos->transform[1][0] * invS1;
+  r[1][1] = pos->transform[1][1] * invS1;
+  r[1][2] = pos->transform[1][2] * invS1;
+  r[2][0] = pos->transform[2][0] * invS2;
+  r[2][1] = pos->transform[2][1] * invS2;
+  r[2][2] = pos->transform[2][2] * invS2;
+
+  // Extract XYZ euler angles (R = Rx * Ry * Rz, column-major)
+  // r[2][0] = sin(Y), r[2][1] = -sin(X)*cos(Y), r[2][2] = cos(X)*cos(Y)
+  // r[0][0] = cos(Y)*cos(Z), r[1][0] = -cos(Y)*sin(Z)
+  float sinBeta = glm_clamp(r[2][0], -1.0f, 1.0f);
+  pos->rotation[1] = asinf(sinBeta);
+  float cosBeta = cosf(pos->rotation[1]);
+
+  if (fabsf(cosBeta) > 1e-6f) {
+    pos->rotation[0] = atan2f(-r[2][1], r[2][2]);
+    pos->rotation[2] = atan2f(-r[1][0], r[0][0]);
+  } else {
+    // Gimbal lock: pin Z to 0, recover X from the remaining degree of freedom
+    pos->rotation[2] = 0.0f;
+    pos->rotation[0] = (sinBeta > 0.0f)
+      ? atan2f(r[0][1], r[1][1])
+      : -atan2f(r[0][1], r[1][1]);
+  }
+}

src/dusk/entity/component/display/entityposition.h

@@ -10,6 +10,9 @@
 
 typedef struct {
   mat4 transform;
+  vec3 position;
+  vec3 rotation;
+  vec3 scale;
 } entityposition_t;
 
 /**
@@ -52,3 +55,96 @@ void entityPositionGetTransform(
   const componentid_t componentId,
   mat4 dest
 );
+
+/**
+ * Gets the cached position of the entity.
+ *
+ * @param entityId The entity ID.
+ * @param componentId The component ID.
+ * @param dest The destination vec3 to write the position to.
+ */
+void entityPositionGetPosition(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 dest
+);
+
+/**
+ * Sets the position of the entity and rebuilds the transform matrix.
+ *
+ * @param entityId The entity ID.
+ * @param componentId The component ID.
+ * @param position The new position.
+ */
+void entityPositionSetPosition(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 position
+);
+
+/**
+ * Gets the cached euler rotation (XYZ, radians) of the entity.
+ *
+ * @param entityId The entity ID.
+ * @param componentId The component ID.
+ * @param dest The destination vec3 to write the rotation to.
+ */
+void entityPositionGetRotation(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 dest
+);
+
+/**
+ * Sets the euler rotation (XYZ, radians) of the entity and rebuilds the
+ * transform matrix.
+ *
+ * @param entityId The entity ID.
+ * @param componentId The component ID.
+ * @param rotation The new euler rotation in radians.
+ */
+void entityPositionSetRotation(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 rotation
+);
+
+/**
+ * Gets the cached scale of the entity.
+ *
+ * @param entityId The entity ID.
+ * @param componentId The component ID.
+ * @param dest The destination vec3 to write the scale to.
+ */
+void entityPositionGetScale(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 dest
+);
+
+/**
+ * Sets the scale of the entity and rebuilds the transform matrix.
+ *
+ * @param entityId The entity ID.
+ * @param componentId The component ID.
+ * @param scale The new scale.
+ */
+void entityPositionSetScale(
+  const entityid_t entityId,
+  const componentid_t componentId,
+  vec3 scale
+);
+
+/**
+ * Internal function to rebuild the transform matrix of the entity position
+ * component based on the current position, rotation, and scale.
+ */
+void entityPositionRebuild(entityposition_t *pos);
+
+/**
+ * Decomposes the transform matrix back into the position, rotation (XYZ euler,
+ * radians), and scale cache fields. Call after any direct matrix modification.
+ *
+ * @param pos Pointer to the entity position component data.
+ */
+void entityPositionDecompose(entityposition_t *pos);