add basic gltf loader

1 files changed, 49 insertions, 18 deletions

diff --git a/src/gltf_loader.cpp b/src/gltf_loader.cpp
index 142b69f..bf64740 100644
--- a/src/gltf_loader.cpp
+++ b/src/gltf_loader.cpp
@@ -1,6 +1,6 @@
 #include "gltf_loader.h"
 #include "spdlog/spdlog.h"
-#include <concepts>
+#include <cstdint>
 
 enum class SceneFileType {
     GLTF,
@@ -79,6 +79,8 @@ bool load_gltf(const std::string_view path, iris::Scene &scene) {
         iris::Mesh iris_mesh {
             .name = mesh.name,
             .vertices = {},
+            .normals = {},
+            .texcoords = {},
             .indices = {},
         };
         for (const auto &primitive : mesh.primitives) {
@@ -87,7 +89,7 @@ bool load_gltf(const std::string_view path, iris::Scene &scene) {
             const auto &index_buffer = model.buffers[index_buffer_view.buffer];
             const uint8_t *index_data_ptr = index_buffer.data.data() + index_buffer_view.byteOffset + index_accessor.byteOffset;
 
-            auto extract_index = [&index_data_ptr]<typename T>() -> T requires std::integral<T> {
+            auto extract = [&index_data_ptr]<typename T>() -> T {
                 const T *index_data = reinterpret_cast<const T *>(index_data_ptr);
                 index_data_ptr += sizeof(T);
                 return *index_data;
@@ -95,32 +97,32 @@ bool load_gltf(const std::string_view path, iris::Scene &scene) {
             switch (index_accessor.componentType) {
                 case TINYGLTF_COMPONENT_TYPE_BYTE:
                     for (size_t i = 0; i < index_accessor.count; i++) {
-                        iris_mesh.indices.push_back(extract_index.operator()<int8_t>());
+                        iris_mesh.indices.push_back(extract.operator()<int8_t>());
                     }
                     break;
                 case TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE:
                     for (size_t i = 0; i < index_accessor.count; i++) {
-                        iris_mesh.indices.push_back(extract_index.operator()<uint8_t>());
+                        iris_mesh.indices.push_back(extract.operator()<uint8_t>());
                     }
                     break;
                 case TINYGLTF_COMPONENT_TYPE_SHORT:
                     for (size_t i = 0; i < index_accessor.count; i++) {
-                        iris_mesh.indices.push_back(extract_index.operator()<int16_t>());
+                        iris_mesh.indices.push_back(extract.operator()<int16_t>());
                     }
                     break;
                 case TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT:
                     for (size_t i = 0; i < index_accessor.count; i++) {
-                        iris_mesh.indices.push_back(extract_index.operator()<uint16_t>());
+                        iris_mesh.indices.push_back(extract.operator()<uint16_t>());
                     }
                     break;
                 case TINYGLTF_COMPONENT_TYPE_INT:
                     for (size_t i = 0; i < index_accessor.count; i++) {
-                        iris_mesh.indices.push_back(extract_index.operator()<int32_t>());
+                        iris_mesh.indices.push_back(extract.operator()<int32_t>());
                     }
                     break;
                 case TINYGLTF_COMPONENT_TYPE_UNSIGNED_INT:
                     for (size_t i = 0; i < index_accessor.count; i++) {
-                        iris_mesh.indices.push_back(extract_index.operator()<uint32_t>());
+                        iris_mesh.indices.push_back(extract.operator()<uint32_t>());
                     }
                     break;
                 default:
@@ -135,7 +137,12 @@ bool load_gltf(const std::string_view path, iris::Scene &scene) {
                         const auto &accessor = model.accessors[accessor_index];
                         const auto &buffer_view = model.bufferViews[accessor.bufferView];
                         const auto &buffer = model.buffers[buffer_view.buffer];
-                        const float *data = reinterpret_cast<const float *>(buffer.data.data() + buffer_view.byteOffset + accessor.byteOffset);
+                        const uint8_t *data = buffer.data.data() + buffer_view.byteOffset + accessor.byteOffset;
+                        auto extract_data = [&data]<typename T>() -> T {
+                            const T *typed_data = reinterpret_cast<const T *>(data);
+                            data += sizeof(T);
+                            return *typed_data;
+                        };
 
                         // TODO: support other types. Currently only float3 is supported
                         if (accessor.type != TINYGLTF_TYPE_VEC3 || accessor.componentType != TINYGLTF_COMPONENT_TYPE_FLOAT) {
@@ -146,24 +153,20 @@ bool load_gltf(const std::string_view path, iris::Scene &scene) {
                         // spdlog::info("attribute: {}, count: {}", attrib_name, accessor.count);
                         if (attrib_name == "POSITION") {
                             spdlog::info("loading POSITION, count {}", accessor.count);
+                            iris_mesh.p_min = glm::vec3(accessor.minValues[0], accessor.minValues[1], accessor.minValues[2]);
+                            iris_mesh.p_max = glm::vec3(accessor.maxValues[0], accessor.maxValues[1], accessor.maxValues[2]);
                             for (size_t i = 0; i < accessor.count; i++) {
-                                iris_mesh.vertices.push_back(data[i * 3 + 0]);
-                                iris_mesh.vertices.push_back(data[i * 3 + 1]);
-                                iris_mesh.vertices.push_back(data[i * 3 + 2]);
+                                iris_mesh.vertices.push_back(extract_data.operator()<glm::vec3>());
                             }
                         } else if (attrib_name == "NORMAL") {
                             spdlog::info("loading NORMAL, count {}", accessor.count);
                             for (size_t i = 0; i < accessor.count; i++) {
-                                iris_mesh.vertices.push_back(data[i * 3 + 0]);
-                                iris_mesh.vertices.push_back(data[i * 3 + 1]);
-                                iris_mesh.vertices.push_back(data[i * 3 + 2]);
+                                iris_mesh.normals.push_back(extract_data.operator()<glm::vec3>());
                             }
-                            // TODO reorder normals correctly
                         } else if (attrib_name == "TEXCOORD_0") {
                             spdlog::info("loading TEXCOORD_0, count {}", accessor.count);
                             for (size_t i = 0; i < accessor.count; i++) {
-                                iris_mesh.vertices.push_back(data[i * 2 + 0]);
-                                iris_mesh.vertices.push_back(data[i * 2 + 1]);
+                                iris_mesh.texcoords.push_back(extract_data.operator()<glm::vec2>());
                             }
                         } else {
                             spdlog::warn("Unsupported attribute: {}", attrib_name);
@@ -179,5 +182,33 @@ bool load_gltf(const std::string_view path, iris::Scene &scene) {
         scene.meshes.push_back(iris_mesh);
     }
 
+    // TODO load materials and textures
+
+    for (const tinygltf::Camera &camera : model.cameras) {
+        iris::Camera iris_camera {
+            .position = glm::vec3(0.0f),
+            .direction = glm::vec3(0.0f),
+            .up = glm::vec3(0.0f, 1.0f, 0.0f),
+        };
+        spdlog::info("Camera: {}, type: {}", camera.name, camera.type);
+        if (camera.type == "perspective") {
+            const auto &perspective = camera.perspective;
+            iris_camera.intrinsic_tag = iris::Camera::Tag::Perspective;
+            iris_camera.intrinsic.perspective.fovx = 2 * glm::atan(glm::tan(perspective.yfov / 2) * perspective.aspectRatio);
+            iris_camera.intrinsic.perspective.fovy = perspective.yfov;
+            iris_camera.intrinsic.perspective.aspect = perspective.aspectRatio;
+            iris_camera.intrinsic.perspective.znear = perspective.znear;
+            iris_camera.intrinsic.perspective.zfar = perspective.zfar;
+        } else {
+            const auto &orthographic = camera.orthographic;
+            iris_camera.intrinsic_tag = iris::Camera::Tag::Orthographic;
+            iris_camera.intrinsic.orthographic.xmag = orthographic.xmag;
+            iris_camera.intrinsic.orthographic.ymag = orthographic.ymag;
+            iris_camera.intrinsic.orthographic.znear = orthographic.znear;
+            iris_camera.intrinsic.orthographic.zfar = orthographic.zfar;
+        }
+        scene.camera = iris_camera;
+    }
+
     return true;
 }
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