src/engine/scene.c

   1 #include <stdlib.h>
   2
   3 #include "engine/logger.h"
   4
   5 #include "scene.h"
   6
   7 Scene* currentScene = NULL;
   8
   9
  10
  11 Transform identity() {
  12         return (Transform) { .a1 = 1.0f, .a2 = 0.0f, .a3 = 0.0f, .a4 = 0.0f,
  13                              .b1 = 0.0f, .b2 = 1.0f, .b3 = 0.0f, .b4 = 0.0f,
  14                              .c1 = 0.0f, .c2 = 0.0f, .c3 = 1.0f, .c4 = 0.0f,
  15                              .d1 = 0.0f, .d2 = 0.0f, .d3 = 0.0f, .d4 = 1.0f };
  16 }
  17
  18 void multiply(Transform* transform, Transform by) {
  19         GLfloat* a = (GLfloat*) &by;
  20         GLfloat* b = (GLfloat*) transform;
  21
  22         for (size_t row = 0; row < 4; ++row) {
  23                 for (size_t col = 0; col < 4; ++col) {
  24                         b[(row * 4) + col] =
  25                                 a[(row * 4) + 0] * b[(0 * 4) + col]
  26                                 + a[(row * 4) + 1] * b[(1 * 4) + col]
  27                                 + a[(row * 4) + 2] * b[(2 * 4) + col]
  28                                 + a[(row * 4) + 3] * b[(3 * 4) + col];
  29                 }
  30         }
  31 }
  32
  33 void translate(Transform* transform, Vector3D vec) {
  34         multiply(transform, (Transform) { .a1 = 1.0f, .a2 = 0.0f, .a3 = 0.0f, .a4 = vec.x,
  35                                       .b1 = 0.0f, .b2 = 1.0f, .b3 = 0.0f, .b4 = vec.y,
  36                                       .c1 = 0.0f, .c2 = 0.0f, .c3 = 1.0f, .c4 = vec.z,
  37                                       .d1 = 0.0f, .d2 = 0.0f, .d3 = 0.0f, .d4 = 1.0f });
  38 }
  39
  40 Vector3D translationOf(Transform transform) {
  41         return (Vector3D) { transform.a4, transform.b4, transform.c4 };
  42 }
  43
  44 Scene* newScene() {
  45         Scene* scene = malloc(sizeof(Scene));
  46         *scene = (Scene) { .parent = NULL,
  47                            .numChildren = 0u,
  48                            .children = NULL,
  49                            .transform = identity(),
  50                            .solid = NULL };
  51         return scene;
  52 }
  53
  54 void insertChildScene(Scene* scene, Scene* newChild) {
  55         if (!scene || !newChild) {
  56                 return;
  57         }
  58         if (newChild->parent) {
  59                 logError(
  60                         "Cannot insert scene 0x%p as child of 0x%p, because it is already child of 0x%p",
  61                         newChild,
  62                         scene,
  63                         newChild->parent);
  64                 return;
  65         }
  66
  67         scene->children = realloc(scene->children, ++(scene->numChildren) * sizeof(Scene*));
  68         scene->children[scene->numChildren - 1] = newChild;
  69
  70         newChild->parent = scene;
  71 }
  72
  73 void reparentScene(Scene* scene, Scene* newParent) {
  74         if (!scene) {
  75                 return;
  76         }
  77
  78         if (scene->parent) {
  79                 Scene* parent = scene->parent;
  80                 size_t indexInParent = parent->numChildren;
  81                 for (size_t i = 0; i < parent->numChildren; ++i) {
  82                         if (parent->children[i] == scene) {
  83                                 indexInParent = i;
  84                                 break;
  85                         }
  86                 }
  87                 // This includes the hopefully impossible case where parent->numChildren == 0
  88                 if (indexInParent == parent->numChildren) {
  89                         logError("Scene %p not found in children of parent %p", scene, parent);
  90                 }
  91                 else {
  92                         for (size_t i = indexInParent; i < parent->numChildren - 1; ++i) {
  93                                 parent->children[i] = parent->children[i + 1];
  94                         }
  95                         parent->children = realloc(parent->children, --(parent->numChildren) * sizeof(Scene*));
  96                 }
  97         }
  98
  99         scene->parent = NULL;
 100
 101         insertChildScene(newParent, scene);
 102 }