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/** ---------------------------------------------------------------------------
* -*- c++ -*-
* @file: camera.cpp
*
* Copyright (c) 2017 Yann Herklotz Grave <ymherklotz@gmail.com>
* MIT License, see LICENSE file for more details.
* ----------------------------------------------------------------------------
*/
#include "camera.h"
#include "../render/shader.h"
#include "logger.h"
#include <glad/glad.h>
#include <glm/gtc/matrix_transform.hpp>
namespace yage
{
/**
* Creates a camera that looks onto the scene. The screen width and screen
* height should be the current size of the window that the camera is being used
* on so that is functions correctly.
*
* @param screen_width Current screen width of the Window.
* @param screen_height Current screen height of the Window.
*/
Camera::Camera(int screen_width, int screen_height)
: position_(0.f, 0.f), camera_matrix_(1.f),
ortho_matrix_(
glm::ortho(0.f, (float)screen_width, 0.f, (float)screen_height))
{
}
/**
* Updates the camera matrix value in the shader program that is passed to it.
* This must be a parameter `P` in the shader for this function to work.
*
* @param program Shader program to make changes to.
*
* @todo Make this function more general to be able to be able to use any
* parametre in then shader as the camera matrix and not make it dependent on it
* being `P`.
*/
void Camera::update(Shader &program)
{
if (update_matrix_) {
glm::vec3 translate(-position_.x, -position_.y, 0.f);
glm::vec3 scale(scale_, scale_, 0.f);
camera_matrix_ = glm::translate(ortho_matrix_, translate);
camera_matrix_ = glm::scale(glm::mat4(1.f), scale) * camera_matrix_;
update_matrix_ = false;
}
program.setUniform("P", camera_matrix_);
}
/**
* Moves the camera using a two-dimensional displacement vector to describe the
* movement.
*
* @param direction Two-dimensional vector to describe the displacement of the
* camera.
*/
void Camera::move(const glm::vec2 &direction)
{
position_ += direction;
update_matrix_ = true;
}
/**
* Zooms the camera by an incremental amount.
*
* @param factor Factor by which the camera should zoom. This can also be a
* negative number for the camera to zoom out.
*/
void Camera::zoom(float factor)
{
scale_ += factor;
update_matrix_ = true;
}
} // namespace yage
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