[models] Add GLTF animation support (#2844)

* add GLTF animation support

* use correct index when allocating animVertices and animNormals

* early exit LoadModelAnimationsGLTF if the gtlf file fails to parse

* update models/models_loading_gltf.c to play gltf animation

Updated the .blend file to use weights rather than bone parents so it
fits into the framework. Exported with weights to the .glb file.

* fix order of operations for bone scale in UpdateModelAnimation

* minor doc cleanup and improvements

* fix formatting

* fix float formatting

* fix brace alignment and replace asserts with log messages

1 files changed, 302 insertions, 18 deletions

diff --git a/src/rmodels.c b/src/rmodels.c
index 9bb54961..ed32751c 100644
--- a/src/rmodels.c
+++ b/src/rmodels.c
@@ -146,7 +146,7 @@ static ModelAnimation *LoadModelAnimationsIQM(const char *fileName, unsigned int
 #endif
 #if defined(SUPPORT_FILEFORMAT_GLTF)
 static Model LoadGLTF(const char *fileName);    // Load GLTF mesh data
-//static ModelAnimation *LoadModelAnimationGLTF(const char *fileName, unsigned int *animCount);    // Load GLTF animation data
+static ModelAnimation *LoadModelAnimationsGLTF(const char *fileName, unsigned int *animCount);    // Load GLTF animation data
 #endif
 #if defined(SUPPORT_FILEFORMAT_VOX)
 static Model LoadVOX(const char *filename);     // Load VOX mesh data
@@ -1955,7 +1955,7 @@ ModelAnimation *LoadModelAnimations(const char *fileName, unsigned int *animCoun
     if (IsFileExtension(fileName, ".m3d")) animations = LoadModelAnimationsM3D(fileName, animCount);
 #endif
 #if defined(SUPPORT_FILEFORMAT_GLTF)
-    //if (IsFileExtension(fileName, ".gltf;.glb")) animations = LoadModelAnimationGLTF(fileName, animCount);
+    if (IsFileExtension(fileName, ".gltf;.glb")) animations = LoadModelAnimationsGLTF(fileName, animCount);
 #endif
 
     return animations;
@@ -2029,8 +2029,8 @@ void UpdateModelAnimation(Model model, ModelAnimation anim, int frame)
                     // Vertices processing
                     // NOTE: We use meshes.vertices (default vertex position) to calculate meshes.animVertices (animated vertex position)
                     animVertex = (Vector3){ mesh.vertices[vCounter], mesh.vertices[vCounter + 1], mesh.vertices[vCounter + 2] };
-                    animVertex = Vector3Multiply(animVertex, outScale);
                     animVertex = Vector3Subtract(animVertex, inTranslation);
+                    animVertex = Vector3Multiply(animVertex, outScale);
                     animVertex = Vector3RotateByQuaternion(animVertex, QuaternionMultiply(outRotation, QuaternionInvert(inRotation)));
                     animVertex = Vector3Add(animVertex, outTranslation);
                     //animVertex = Vector3Transform(animVertex, model.transform);
@@ -3829,6 +3829,25 @@ RayCollision GetRayCollisionQuad(Ray ray, Vector3 p1, Vector3 p2, Vector3 p3, Ve
     return collision;
 }
 
+static void BuildPoseFromParentJoints(BoneInfo *bones, int boneCount, Transform *transforms)
+{
+    for (int i = 0; i < boneCount; i++)
+    {
+        if (bones[i].parent >= 0)
+        {
+            if (bones[i].parent > i)
+            {
+                TRACELOG(LOG_WARNING, "Assumes bones are toplogically sorted, but bone %d has parent %d. Skipping.", i, bones[i].parent);
+                continue;
+            }
+            transforms[i].rotation = QuaternionMultiply(transforms[bones[i].parent].rotation, transforms[i].rotation);
+            transforms[i].translation = Vector3RotateByQuaternion(transforms[i].translation, transforms[bones[i].parent].rotation);
+            transforms[i].translation = Vector3Add(transforms[i].translation, transforms[bones[i].parent].translation);
+            transforms[i].scale = Vector3Multiply(transforms[i].scale, transforms[bones[i].parent].scale);
+        }
+    }
+}
+
 //----------------------------------------------------------------------------------
 // Module specific Functions Definition
 //----------------------------------------------------------------------------------
@@ -4370,17 +4389,7 @@ static Model LoadIQM(const char *fileName)
         model.bindPose[i].scale.z = ijoint[i].scale[2];
     }
 
-    // Build bind pose from parent joints
-    for (int i = 0; i < model.boneCount; i++)
-    {
-        if (model.bones[i].parent >= 0)
-        {
-            model.bindPose[i].rotation = QuaternionMultiply(model.bindPose[model.bones[i].parent].rotation, model.bindPose[i].rotation);
-            model.bindPose[i].translation = Vector3RotateByQuaternion(model.bindPose[i].translation, model.bindPose[model.bones[i].parent].rotation);
-            model.bindPose[i].translation = Vector3Add(model.bindPose[i].translation, model.bindPose[model.bones[i].parent].translation);
-            model.bindPose[i].scale = Vector3Multiply(model.bindPose[i].scale, model.bindPose[model.bones[i].parent].scale);
-        }
-    }
+    BuildPoseFromParentJoints(model.bones, model.boneCount, model.bindPose);
 
     RL_FREE(fileData);
 
@@ -4681,6 +4690,33 @@ static Image LoadImageFromCgltfImage(cgltf_image *cgltfImage, const char *texPat
     return image;
 }
 
+static BoneInfo *LoadGLTFBoneInfo(cgltf_skin skin, int *boneCount)
+{
+    *boneCount = skin.joints_count;
+    BoneInfo *bones = RL_MALLOC(skin.joints_count*sizeof(BoneInfo));
+
+    for (unsigned int i = 0; i < skin.joints_count; i++)
+    {
+        cgltf_node node = *skin.joints[i];
+        strncpy(bones[i].name, node.name, sizeof(bones[i].name));
+
+        // find parent bone index
+        unsigned int parentIndex = -1;
+        for (unsigned int j = 0; j < skin.joints_count; j++)
+        {
+            if (skin.joints[j] == node.parent)
+            {
+                parentIndex = j;
+                break;
+            }
+        }
+
+        bones[i].parent = parentIndex;
+    }
+
+    return bones;
+}
+
 // Load glTF file into model struct, .gltf and .glb supported
 static Model LoadGLTF(const char *fileName)
 {
@@ -4695,6 +4731,7 @@ static Model LoadGLTF(const char *fileName)
           - Supports PBR metallic/roughness flow, loads material textures, values and colors
                      PBR specular/glossiness flow and extended texture flows not supported
           - Supports multiple meshes per model (every primitives is loaded as a separate mesh)
+          - Supports basic animation
 
         RESTRICTIONS:
           - Only triangle meshes supported
@@ -5039,11 +5076,41 @@ static Model LoadGLTF(const char *fileName)
             }
         }
 
-/*
-        // TODO: Load glTF meshes animation data
+        // Load glTF meshes animation data
         // REF: https://www.khronos.org/registry/glTF/specs/2.0/glTF-2.0.html#skins
         // REF: https://www.khronos.org/registry/glTF/specs/2.0/glTF-2.0.html#skinned-mesh-attributes
         //----------------------------------------------------------------------------------------------------
+
+        if (data->skins_count == 1)
+        {
+            cgltf_skin skin = data->skins[0];
+            model.bones = LoadGLTFBoneInfo(skin, &model.boneCount);
+            model.bindPose = RL_MALLOC(model.boneCount*sizeof(Transform));
+
+            for (unsigned int i = 0; i < model.boneCount; i++)
+            {
+                cgltf_node node = *skin.joints[i];
+                model.bindPose[i].translation.x = node.translation[0];
+                model.bindPose[i].translation.y = node.translation[1];
+                model.bindPose[i].translation.z = node.translation[2];
+
+                model.bindPose[i].rotation.x = node.rotation[0];
+                model.bindPose[i].rotation.y = node.rotation[1];
+                model.bindPose[i].rotation.z = node.rotation[2];
+                model.bindPose[i].rotation.w = node.rotation[3];
+
+                model.bindPose[i].scale.x = node.scale[0];
+                model.bindPose[i].scale.y = node.scale[1];
+                model.bindPose[i].scale.z = node.scale[2];
+            }
+
+            BuildPoseFromParentJoints(model.bones, model.boneCount, model.bindPose);
+        }
+        else if (data->skins_count > 1)
+        {
+            TRACELOG(LOG_ERROR, "MODEL: [%s] can only load one skin (armature) per model, but gltf skins_count == %i", fileName, data->skins_count);
+        }
+
         for (unsigned int i = 0, meshIndex = 0; i < data->meshes_count; i++)
         {
             for (unsigned int p = 0; p < data->meshes[i].primitives_count; p++)
@@ -5065,7 +5132,6 @@ static Model LoadGLTF(const char *fileName)
                             model.meshes[meshIndex].boneIds = RL_CALLOC(model.meshes[meshIndex].vertexCount*4, sizeof(unsigned char));
 
                             // Load 4 components of unsigned char data type into mesh.boneIds
-                            // TODO: It seems LOAD_ATTRIBUTE() macro does not work as expected in some cases,
                             // for cgltf_attribute_type_joints we have:
                             //   - data.meshes[0] (256 vertices)
                             //   - 256 values, provided as cgltf_type_vec4 of bytes (4 byte per joint, stride 4)
@@ -5092,10 +5158,17 @@ static Model LoadGLTF(const char *fileName)
                     }
                 }
 
+                // Animated vertex data
+                model.meshes[meshIndex].animVertices = RL_CALLOC(model.meshes[meshIndex].vertexCount*3, sizeof(float));
+                memcpy(model.meshes[meshIndex].animVertices, model.meshes[meshIndex].vertices, model.meshes[meshIndex].vertexCount*3*sizeof(float));
+                model.meshes[meshIndex].animNormals = RL_CALLOC(model.meshes[meshIndex].vertexCount*3, sizeof(float));
+                memcpy(model.meshes[meshIndex].animNormals, model.meshes[meshIndex].normals, model.meshes[meshIndex].vertexCount*3*sizeof(float));
+
                 meshIndex++;       // Move to next mesh
             }
+
         }
-*/
+
         // Free all cgltf loaded data
         cgltf_free(data);
     }
@@ -5106,6 +5179,217 @@ static Model LoadGLTF(const char *fileName)
 
     return model;
 }
+
+// Get interpolated pose for bone sampler at a specific time. Returns true on success.
+static bool GetGLTFPoseAtTime(cgltf_accessor* input, cgltf_accessor *output, float time, void *data)
+{
+    // input and output should have the same count
+
+    float tstart = 0.0f;
+    float tend = 0.0f;
+
+    int keyframe = 0; // defaults to first pose
+    for (int i = 0; i < input->count - 1; i++)
+    {
+        cgltf_bool r1 = cgltf_accessor_read_float(input, i, &tstart, 1);
+        if (!r1) return false;
+        cgltf_bool r2 = cgltf_accessor_read_float(input, i+1, &tend, 1);
+        if (!r2) return false;
+
+        if ((tstart <= time) && (time < tend))
+        {
+            keyframe = i;
+            break;
+        }
+    }
+
+    float t = (time - tstart)/(tend - tstart);
+    t = (t < 0.0f)? 0.0f : t;
+    t = (t > 1.0f)? 1.0f : t;
+
+    if (output->component_type != cgltf_component_type_r_32f) return false;
+
+    if (output->type == cgltf_type_vec3)
+    {
+        float tmp[3] = { 0.0f };
+        cgltf_accessor_read_float(output, keyframe, tmp, 3);
+        Vector3 v1 = {tmp[0], tmp[1], tmp[2]};
+        cgltf_accessor_read_float(output, keyframe+1, tmp, 3);
+        Vector3 v2 = {tmp[0], tmp[1], tmp[2]};
+        Vector3 *r = data;
+        *r = Vector3Lerp(v1, v2, t);
+    }
+    else if (output->type == cgltf_type_vec4)
+    {
+        float tmp[4] = { 0.0f };
+        cgltf_accessor_read_float(output, keyframe, tmp, 4);
+        Vector4 v1 = {tmp[0], tmp[1], tmp[2], tmp[3]};
+        cgltf_accessor_read_float(output, keyframe+1, tmp, 4);
+        Vector4 v2 = {tmp[0], tmp[1], tmp[2], tmp[3]};
+        Vector4 *r = data;
+        // only v4 is for rotations, so we know it's a quat.
+        *r = QuaternionSlerp(v1, v2, t);
+    }
+    return true;
+}
+
+#define GLTF_ANIMDELAY 17    // that's roughly ~1000 msec / 60 FPS (16.666666* msec)
+static ModelAnimation *LoadModelAnimationsGLTF(const char *fileName, unsigned int *animCount)
+{
+    // glTF file loading
+    unsigned int dataSize = 0;
+    unsigned char *fileData = LoadFileData(fileName, &dataSize);
+
+    ModelAnimation *animations = NULL;
+    // glTF data loading
+    cgltf_options options = { 0 };
+    cgltf_data *data = NULL;
+    cgltf_result result = cgltf_parse(&options, fileData, dataSize, &data);
+    if (result != cgltf_result_success)
+    {
+        TRACELOG(LOG_WARNING, "MODEL: [%s] Failed to load glTF data", fileName);
+        *animCount = 0;
+        return NULL;
+    }
+
+    result = cgltf_load_buffers(&options, data, fileName);
+    if (result != cgltf_result_success) TRACELOG(LOG_INFO, "MODEL: [%s] Failed to load animation buffers", fileName);
+
+    if (result == cgltf_result_success)
+    {
+        if (data->skins_count == 1)
+        {
+            cgltf_skin skin = data->skins[0];
+            *animCount = data->animations_count;
+            animations = RL_MALLOC(data->animations_count*sizeof(ModelAnimation));
+            for (unsigned int i = 0; i < data->animations_count; i++)
+            {
+                animations[i].bones = LoadGLTFBoneInfo(skin, &animations[i].boneCount);
+
+                cgltf_animation animData = data->animations[i];
+
+                struct Channels {
+                    cgltf_animation_channel *translate;
+                    cgltf_animation_channel *rotate;
+                    cgltf_animation_channel *scale;
+                };
+
+                struct Channels *boneChannels = RL_CALLOC(animations[i].boneCount, sizeof(struct Channels));
+                float animDuration = 0.0f;
+                for (unsigned int j = 0; j < animData.channels_count; j++)
+                {
+                    cgltf_animation_channel channel = animData.channels[j];
+                    int boneIndex = -1;
+                    for (unsigned int k = 0; k < skin.joints_count; k++)
+                    {
+                        if (animData.channels[j].target_node == skin.joints[k])
+                        {
+                            boneIndex = k;
+                            break;
+                        }
+                    }
+
+                    if (boneIndex == -1)
+                    {
+                        // animation channel for a node not in the armature.
+                        continue;
+                    }
+
+                    if (animData.channels[j].sampler->interpolation == cgltf_interpolation_type_linear)
+                    {
+                        if (channel.target_path == cgltf_animation_path_type_translation)
+                        {
+                            boneChannels[boneIndex].translate = &animData.channels[j];
+                        }
+                        else if (channel.target_path == cgltf_animation_path_type_rotation)
+                        {
+                            boneChannels[boneIndex].rotate = &animData.channels[j];
+                        }
+                        else if (channel.target_path == cgltf_animation_path_type_scale)
+                        {
+                            boneChannels[boneIndex].scale = &animData.channels[j];
+                        }
+                        else
+                        {
+                            TRACELOG(LOG_WARNING, "MODEL: [%s] Unsupported target_path on channel %d's sampler for animation %d. Skipping.", fileName, j, i);
+                        }
+                    } else TRACELOG(LOG_WARNING, "MODEL: [%s] Only linear interpolation curves are supported for GLTF animation.", fileName);
+
+                    float t = 0.0f;
+                    cgltf_bool r = cgltf_accessor_read_float(channel.sampler->input, channel.sampler->input->count - 1, &t, 1);
+                    if (!r)
+                    {
+                        TRACELOG(LOG_WARNING, "MODEL: [%s] Failed to load input time", fileName);
+                        continue;
+                    }
+
+                    animDuration = (t > animDuration)? t : animDuration;
+                }
+
+                animations[i].frameCount = (int)(animDuration*1000.0f/GLTF_ANIMDELAY);
+                animations[i].framePoses = RL_MALLOC(animations[i].frameCount*sizeof(Transform *));
+
+                for (unsigned int j = 0; j < animations[i].frameCount; j++)
+                {
+                    animations[i].framePoses[j] = RL_MALLOC(animations[i].boneCount*sizeof(Transform));
+                    float time = ((float) j*GLTF_ANIMDELAY)/1000.0f;
+                    for (unsigned int k = 0; k < animations[i].boneCount; k++)
+                    {
+                        Vector3 translation = {0, 0, 0};
+                        Quaternion rotation = {0, 0, 0, 1};
+                        Vector3 scale = {1, 1, 1};
+                        if (boneChannels[k].translate)
+                        {
+                            if (!GetGLTFPoseAtTime(boneChannels[k].translate->sampler->input,
+                                        boneChannels[k].translate->sampler->output,
+                                        time,
+                                        &translation))
+                            {
+                                TRACELOG(LOG_INFO, "MODEL: [%s] Failed to load translate pose data for bone %s", fileName, animations[i].bones[k].name);
+                            }
+                        }
+
+                        if (boneChannels[k].rotate)
+                        {
+                            if (!GetGLTFPoseAtTime(boneChannels[k].rotate->sampler->input,
+                                    boneChannels[k].rotate->sampler->output,
+                                    time,
+                                    &rotation))
+                            {
+                                TRACELOG(LOG_INFO, "MODEL: [%s] Failed to load rotate pose data for bone %s", fileName, animations[i].bones[k].name);
+                            }
+                        }
+
+                        if (boneChannels[k].scale)
+                        {
+                            if (!GetGLTFPoseAtTime(boneChannels[k].scale->sampler->input,
+                                    boneChannels[k].scale->sampler->output,
+                                    time,
+                                    &scale))
+                            {
+                                TRACELOG(LOG_INFO, "MODEL: [%s] Failed to load scale pose data for bone %s", fileName, animations[i].bones[k].name);
+                            }
+                        }
+
+                        animations[i].framePoses[j][k] = (Transform){
+                            .translation = translation,
+                            .rotation = rotation,
+                            .scale = scale};
+                    }
+
+                    BuildPoseFromParentJoints(animations[i].bones, animations[i].boneCount, animations[i].framePoses[j]);
+                }
+
+                TRACELOG(LOG_INFO, "MODEL: [%s] Loaded animation: %s (%d frames, %fs)", fileName, animData.name, animations[i].frameCount, animDuration);
+                RL_FREE(boneChannels);
+            }
+        } else TRACELOG(LOG_ERROR, "MODEL: [%s] expected exactly one skin to load animation data from, but found %i", fileName, data->skins_count);
+
+        cgltf_free(data);
+    }
+
+    return animations;
+}
 #endif
 
 #if defined(SUPPORT_FILEFORMAT_VOX)