transforms.hpp

/*
 * eos - A 3D Morphable Model fitting library written in modern C++11/14.
 *
 * File: include/eos/render/transforms.hpp
 *
 * Copyright 2014, 2015, 2023 Patrik Huber
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#pragma once
 
#ifndef EOS_RENDER_TRANSFORMS_HPP
#define EOS_RENDER_TRANSFORMS_HPP
 
#include "Eigen/Core"
 
namespace eos {
namespace render {
 
inline Eigen::Vector2f clip_to_screen_space(const Eigen::Vector2f& clip_coordinates, int screen_width,
                                            int screen_height)
{
    // Window transform:
    const float x_ss = (clip_coordinates[0] + 1.0f) * (screen_width / 2.0f);
    const float y_ss =
        screen_height - (clip_coordinates[1] + 1.0f) *
                            (screen_height / 2.0f); // also flip y; Qt: Origin top-left. OpenGL: bottom-left.
    return Eigen::Vector2f(x_ss, y_ss);
    /* Note: What we do here is equivalent to
       x_w = (x *  vW/2) + vW/2;
       However, Shirley says we should do:
       x_w = (x *  vW/2) + (vW-1)/2;
       (analogous for y)
       Todo: Check the consequences.
    */
};
 
// Equivalent to the above, but templated, and taking clip_coord_x and _y separately.
// Todo: Can merge this back into one function I think?
template <typename T>
Eigen::Vector2<T> clip_to_screen_space(const T clip_coord_x, const T clip_coord_y, int screen_width,
                                       int screen_height)
{
    // Window transform:
    const T x_ss = (clip_coord_x + T(1)) * (screen_width / 2.0);
    const T y_ss =
        screen_height - (clip_coord_y + T(1)) *
                            (screen_height / 2.0); // also flip y; Qt: Origin top-left. OpenGL: bottom-left.
    return Eigen::Vector2<T>(x_ss, y_ss);
};
 
/*inline cv::Vec2f screen_to_clip_space(const cv::Vec2f& screen_coordinates, int screen_width, int screen_height)
{
    const float x_cs = screen_coordinates[0] / (screen_width / 2.0f) - 1.0f;
    float y_cs = screen_coordinates[1] / (screen_height / 2.0f) - 1.0f;
    y_cs *= -1.0f;
    return cv::Vec2f(x_cs, y_cs);
};*/
 
} /* namespace render */
} /* namespace eos */
 
#endif /* EOS_RENDER_TRANSFORMS_HPP */