Method parse_camera

src/Scene/SceneParser.cpp:227–284

}

void SceneParser::parse_camera(const aiScene* scene, Scene& parsed_scene, float frame_aspect_override)
{
    // Taking the first camera as the camera of the scene
    if (scene->mNumCameras > 0)
    {
        aiCamera* camera = scene->mCameras[0];

        glm::vec3 camera_position = *reinterpret_cast<glm::vec3*>(&camera->mPosition);
        glm::vec3 camera_lookat = *reinterpret_cast<glm::vec3*>(&camera->mLookAt);
        glm::vec3 camera_up = *reinterpret_cast<glm::vec3*>(&camera->mUp);

        // Inversing the lookat because glm::lookat creates a world->view matrix which means
        // that the position of the camera in world->view matrix is going to be '-true_position'
        // 
        // Same for the other properties of the matrix
        glm::mat4x4 lookat = glm::inverse(glm::lookAt(camera_position, camera_lookat, camera_up));

        glm::vec3 scale, skew, translation;
        glm::vec4 perspective;
        glm::quat orientation;
        glm::decompose(lookat, scale, orientation, translation, skew, perspective);

        parsed_scene.camera.m_translation = translation;
        parsed_scene.camera.m_rotation = orientation;

        float aspect_ratio = frame_aspect_override == -1 ? camera->mAspect : frame_aspect_override;
        float vertical_fov = 2.0f * std::atan(std::tan(camera->mHorizontalFOV * 0.5f) * aspect_ratio) + 0.425f;
        parsed_scene.camera.projection_matrix = glm::perspective(vertical_fov, aspect_ratio, camera->mClipPlaneNear, camera->mClipPlaneFar);
        parsed_scene.camera.vertical_fov = vertical_fov;

        // Custom clip planes distances are not supported by the renderer so hardcoding to 0.1f and 100.0f
        // instead of reading from the camera properties
        parsed_scene.camera.near_plane = 0.1f;// camera->mClipPlaneNear;
        parsed_scene.camera.far_plane = 100.0f;// camera->mClipPlaneFar;
    }
    else
    {
        // Creating a default camera because the scene doesn't have one

        glm::mat4x4 lookat = glm::inverse(glm::lookAt(glm::vec3(0, 0, 0), glm::vec3(0, 0, -1), glm::vec3(0, 1, 0)));

        glm::vec3 scale, skew, translation;
        glm::vec4 perspective;
        glm::quat orientation;
        glm::decompose(lookat, scale, orientation, translation, skew, perspective);

        parsed_scene.camera.m_translation = translation;
        parsed_scene.camera.m_rotation = orientation;

        float aspect_ratio = 1280.0f / 720.0f;
        float horizontal_fov = 40.0f / 180 * M_PI;
        float vertical_fov = 2.0f * std::atan(std::tan(horizontal_fov * 0.5f) * aspect_ratio) + 0.425f;
        parsed_scene.camera.projection_matrix = glm::perspective(vertical_fov, aspect_ratio, 0.1f, 100.0f);
        parsed_scene.camera.vertical_fov = vertical_fov;
        parsed_scene.camera.near_plane = 0.1f;
        parsed_scene.camera.far_plane = 100.0f;
    }
}