Gltf animation support (#1551)

* Added example for gltf animation and split some functions for loading model animations into IQM and GLTF similar to how models are being loaded.

* Removed wrongly duplicated function

* Bone loading for gltf model (not working at this point)

* Loading info about vertex to joint connection but animation is still not working

* Skeleton and pose is correctly loaded. Need to communicate about interpolation in GLTF

* The model almost looks like a real person on animation.

* Fixed model loading with bones.

Also updated license info on the model.

* Cleaned up some code and updated examples.

* Fix identation issues

* Fix identation issues

* Fix identation issues

5 files changed, 213 insertions, 0 deletions

diff --git a/examples/models/models_gltf_animation.c b/examples/models/models_gltf_animation.c
new file mode 100644
index 00000000..e3120500
--- /dev/null
+++ b/examples/models/models_gltf_animation.c
@@ -0,0 +1,115 @@
+/*******************************************************************************************
+*
+*   raylib [models] example - Load 3d gltf model with animations and play them
+*
+*   This example has been created using raylib 3.5 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Example contributed by Hristo Stamenov (@object71) and reviewed by Ramon Santamaria (@raysan5)
+*
+*   Copyright (c) 2021 Hristo Stamenov (@object71) and Ramon Santamaria (@raysan5)
+*
+********************************************************************************************
+*
+* To export a model from blender, make sure it is not posed, the vertices need to be in the 
+* same position as they would be in edit mode.
+* and that the scale of your models is set to 0. Scaling can be done from the export menu.
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#include <stdlib.h>
+
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [models] example - model animation");
+
+    // Define the camera to look into our 3d world
+    Camera camera = { 0 };
+    camera.position = (Vector3){ 10.0f, 10.0f, 10.0f }; // Camera position
+    camera.target = (Vector3){ 0.0f, 0.0f, 0.0f };      // Camera looking at point
+    camera.up = (Vector3){ 0.0f, 1.0f, 0.0f };          // Camera up vector (rotation towards target)
+    camera.fovy = 45.0f;                                // Camera field-of-view Y
+    camera.type = CAMERA_PERSPECTIVE;                   // Camera mode type
+
+    Model model = LoadModel("resources/gltf/rigged_figure.glb");               // Load the animated model mesh and
+    // basic data
+//    Texture2D texture = LoadTexture("resources/guy/guytex.png");    // Load model texture and set material
+//    SetMaterialTexture(&model.materials[0], MAP_DIFFUSE, texture);  // Set model material map texture
+
+    Vector3 position = { 0.0f, 0.0f, 0.0f };            // Set model position
+
+    // Load animation data
+    int animsCount = 0;
+    ModelAnimation *anims = LoadModelAnimations("resources/gltf/rigged_figure.glb", &animsCount);
+    int animFrameCounter = 0;
+
+    SetCameraMode(camera, CAMERA_FREE); // Set free camera mode
+
+    SetTargetFPS(60);                   // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())        // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        UpdateCamera(&camera);
+
+        // Play animation when spacebar is held down
+        if (IsKeyDown(KEY_SPACE))
+        {
+            animFrameCounter++;
+            UpdateModelAnimation(model, anims[0], animFrameCounter);
+            if (animFrameCounter >= anims[0].frameCount) animFrameCounter = 0;
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+             ClearBackground(RAYWHITE);
+
+            BeginMode3D(camera);
+
+                DrawModelEx(model, position, (Vector3){ 1.0f, 0.0f, 0.0f }, -90.0f, (Vector3){ 1.0f, 1.0f, 1.0f }, WHITE);
+
+                for (int i = 0; i < model.boneCount; i++)
+                {
+                    DrawSphere(anims[0].framePoses[animFrameCounter][i].translation, 0.01f, RED);
+                }
+
+                DrawGrid(10, 1.0f);         // Draw a grid
+
+            EndMode3D();
+
+            DrawText("PRESS SPACE to PLAY MODEL ANIMATION", 10, 10, 20, MAROON);
+            DrawText("(cc4) Rigged Figure by @Cesium", screenWidth - 200, screenHeight - 20, 10, GRAY);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+//    UnloadTexture(texture);     // Unload texture
+    
+    // Unload model animations data
+    for (int i = 0; i < animsCount; i++) UnloadModelAnimation(anims[i]);
+    RL_FREE(anims);
+
+    UnloadModel(model);         // Unload model
+
+    CloseWindow();              // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}
diff --git a/examples/models/models_gltf_model.c b/examples/models/models_gltf_model.c
new file mode 100644
index 00000000..c064e34f
--- /dev/null
+++ b/examples/models/models_gltf_model.c
@@ -0,0 +1,87 @@
+/*******************************************************************************************
+*
+*   raylib [models] example - Load 3d gltf model
+*
+*   This example has been created using raylib 3.5 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Example contributed by Hristo Stamenov (@object71) and reviewed by Ramon Santamaria (@raysan5)
+*
+*   Copyright (c) 2021 Hristo Stamenov (@object71) and Ramon Santamaria (@raysan5)
+*
+********************************************************************************************
+*
+* To export a model from blender, make sure it is not posed, the vertices need to be in the 
+* same position as they would be in edit mode.
+* and that the scale of your models is set to 0. Scaling can be done from the export menu.
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#include <stdlib.h>
+
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [models] example - model animation");
+
+    // Define the camera to look into our 3d world
+    Camera camera = { 0 };
+    camera.position = (Vector3){ 10.0f, 10.0f, 10.0f }; // Camera position
+    camera.target = (Vector3){ 0.0f, 0.0f, 0.0f };      // Camera looking at point
+    camera.up = (Vector3){ 0.0f, 1.0f, 0.0f };          // Camera up vector (rotation towards target)
+    camera.fovy = 45.0f;                                // Camera field-of-view Y
+    camera.type = CAMERA_PERSPECTIVE;                   // Camera mode type
+
+    Model model = LoadModel("resources/gltf/Avocado.glb");               // Load the animated model mesh and
+
+    Vector3 position = { 0.0f, 0.0f, 0.0f };            // Set model position
+
+    SetCameraMode(camera, CAMERA_FREE); // Set free camera mode
+
+    SetTargetFPS(60);                   // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())        // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        UpdateCamera(&camera);
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+             ClearBackground(RAYWHITE);
+
+            BeginMode3D(camera);
+
+                DrawModelEx(model, position, (Vector3){ 0.0f, 1.0f, 0.0f }, 180.0f, (Vector3){ 15.0f, 15.0f, 15.0f }, WHITE);
+
+                DrawGrid(10, 1.0f);         // Draw a grid
+
+            EndMode3D();
+
+            DrawText("(cc0) Avocado by @Microsoft", screenWidth - 200, screenHeight - 20, 10, GRAY);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+
+    UnloadModel(model);         // Unload model
+
+    CloseWindow();              // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}
diff --git a/examples/models/resources/gltf/Avocado.glb b/examples/models/resources/gltf/Avocado.glb
new file mode 100644
index 00000000..006b79c3
--- /dev/null
+++ b/examples/models/resources/gltf/Avocado.glb
diff --git a/examples/models/resources/gltf/LICENSE b/examples/models/resources/gltf/LICENSE
new file mode 100644
index 00000000..77c73c62
--- /dev/null
+++ b/examples/models/resources/gltf/LICENSE
@@ -0,0 +1,11 @@
+Rigged Figure model has been created by Cesium (https://cesium.com/cesiumjs/),
+and licensed as Creative Commons Attribution 4.0 International License.
+
+Check for details: http://creativecommons.org/licenses/by/4.0/
+
+Avocado model is provided by Microsoft
+and licensed as CC0 Universal Public Domain
+
+Check for details: https://creativecommons.org/publicdomain/zero/1.0/
+
+GLTF sample models for testing are taken from: https://github.com/KhronosGroup/glTF-Sample-Models/
diff --git a/examples/models/resources/gltf/rigged_figure.glb b/examples/models/resources/gltf/rigged_figure.glb
new file mode 100644
index 00000000..c505a33d
--- /dev/null
+++ b/examples/models/resources/gltf/rigged_figure.glb