关于C#：在SFML中未使用sprite显示的图像

Images not displayed using sprites in SFML

我已经使用C 17在Linux Mint 18.1上学习了SFML 2.3.2，以学习如何使用GUI。作为Hello World之后的第二个项目，我试图重现Snake，即旧手机已预装的游戏。到目前为止，大多数内容都可以使用，除了一些较小的例外，我稍后必须处理，其中一些是由于游戏尚未完全完成引起的。

请确保我理解正确，因为我以前从未使用过低级语言来处理GUI和图像。首先，将图像加载到纹理中，然后将纹理添加到sprite中，然后将该sprite绘制到窗口上？

该程序可以完美编译，正确初始化所有内容，并且运行时没有重大无法解释的问题。除非图像不显示。sprite在那里并以其默认的单色背景色显示，但不显示任何图像。

我该怎么做，以及如何解决？谢谢！

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// HEADERS
#include <iostream>
#include <SFML/Graphics.hpp>
#include <SFML/Graphics/Color.hpp>
#include <SFML/Graphics/Font.hpp>
#include <SFML/Graphics/Image.hpp>
#include <SFML/Graphics/Rect.hpp>
#include <SFML/Graphics/Sprite.hpp>
#include <SFML/Graphics/Texture.hpp>
#include <SFML/System/String.hpp>
#include <SFML/Window/Keyboard.hpp>

// CREATE NEW FONT
sf::Font create_font()
{
sf::Font f;
bool id = f.loadFromFile("/usr/share/fonts/truetype/ubuntu-font-family/Ubuntu-B.ttf");

if (id == false)
{
std::cerr <<"Font:\\tCould not be loaded." << std::endl;
}
else
{
std::cerr <<"Font:\\tLoaded successfully." << std::endl;
}

return f;

}

// CREATE NEW SPRITE USING TEXTURE, GIVEN ARE PATH WITH COORDINATES AND DIMENSIONS
sf::Sprite load_img(std::string path, long x, long y, long w, long h)
{
sf::Texture t;
bool id = t.loadFromFile(path);

if (id == false)
{
std::cerr <<"Texture:\\t" << path <<"\\tFailed to load." << std::endl;
}
else
{
std::cerr <<"Texture:\\t" << path <<"\\tLoaded successfully." << std::endl;
}

sf::Sprite s(t);
s.setTextureRect(sf::IntRect((int)x, (int)y, (int)w, (int)h));
s.setPosition(x, y);
return s;
}

// MAIN FUNCTION
int main()
{
// DECLARING/DEFINING VARIABLES
unsigned long window_width = 512;
unsigned long window_height = 512;
unsigned long score = 0;
unsigned long head_old_position_x, head_old_position_y;
std::string title ="Snek";
std::string wdir ="/home/kate/Documents/coding/snek/";

// WINDOW
sf::RenderWindow window(sf::VideoMode(window_width, window_height), title);
window.setFramerateLimit(60);

// SPRITES
sf::Sprite background = load_img(wdir +"img/background.png", 0, 0, 512, 512);
sf::Sprite head = load_img(wdir +"img/head.png", 47, 39, 8, 8);
sf::Sprite body = load_img(wdir +"img/body.png", 39, 39, 8, 8);
sf::Sprite poison = load_img(wdir +"img/poison.png", 119, 119, 8, 8);
sf::Sprite trap = load_img(wdir +"img/trap.png", 159, 159, 8, 8);
sf::Sprite candy = load_img(wdir +"img/candy.png", 199, 199, 8, 8);

// FONT
sf::Font font = create_font();

// TEXT
sf::Text score_display(title, font, 20);
sc// HEADERS
#include <iostream>
#include <SFML/Graphics.hpp>
#include <SFML/Graphics/Color.hpp>
#include <SFML/Graphics/Font.hpp>
#include <SFML/Graphics/Image.hpp>
#include <SFML/Graphics/Rect.hpp>
#include <SFML/Graphics/Sprite.hpp>
#include <SFML/Graphics/Texture.hpp>
#include <SFML/System/String.hpp>
#include <SFML/Window/Keyboard.hpp>

// CREATE NEW FONT
sf::Font create_font()
{
sf::Font f;
bool id = f.loadFromFile("/usr/share/fonts/truetype/ubuntu-font-family/Ubuntu-B.ttf");

if (id == false)
{
std::cerr <<"Font:\\tCould not be loaded." << std::endl;
}
else
{
std::cerr <<"Font:\\tLoaded successfully." << std::endl;
}

return f;

}

// CREATE NEW SPRITE USING TEXTURE, GIVEN ARE PATH WITH COORDINATES AND DIMENSIONS
sf::Sprite load_img(std::string path, long x, long y, long w, long h)
{
sf::Texture t;
bool id = t.loadFromFile(path);

if (id == false)
{
std::cerr <<"Texture:\\t" << path <<"\\tFailed to load." << std::endl;
}
else
{
std::cerr <<"Texture:\\t" << path <<"\\tLoaded successfully." << std::endl;
}

sf::Sprite s(t);
s.setTextureRect(sf::IntRect((int)x, (int)y, (int)w, (int)h));
s.setPosition(x, y);
return s;
}

// MAIN FUNCTION
int main()
{
// DECLARING/DEFINING VARIABLES
unsigned long window_width = 512;
unsigned long window_height = 512;
unsigned long score = 0;
unsigned long head_old_position_x, head_old_position_y;
std::string title ="Snek";
std::string wdir ="/home/kate/Documents/coding/snek/";

// WINDOW
sf::RenderWindow window(sf::VideoMode(window_width, window_height), title);
window.setFramerateLimit(60);

// SPRITES
sf::Sprite background = load_img(wdir +"/img/background.png", 0, 0, 512, 512);
sf::Sprite head = load_img(wdir +"/img/head.png", 47, 39, 8, 8);
sf::Sprite body = load_img(wdir +"/img/body.png", 39, 39, 8, 8);
sf::Sprite poison = load_img(wdir +"/img/poison.png", 119, 119, 8, 8);
sf::Sprite trap = load_img(wdir +"/img/trap.png", 159, 159, 8, 8);
sf::Sprite candy = load_img(wdir +"/img/candy.png", 199, 199, 8, 8);

// FONT
sf::Font font = create_font();

// TEXT
sf::Text score_display(title, font, 20);
score_display.setString(std::to_string(score));
score_display.setPosition(5, 5);

// LOOP
while (window.isOpen())
{
sf::Event event;
while ( window.pollEvent(event))
{
if (event.type == sf::Event::Closed)
{ window.close(); }

head_old_position_x = head.getPosition().x;
head_old_position_y = head.getPosition().y;

// MOVEMENT BASED ON KEYBOARD INPUT
if (sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
{
head.setPosition(head.getPosition().x - 8, head.getPosition().y);
body.setPosition(head_old_position_x, head_old_position_y);
}

if (sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
{
head.setPosition(head.getPosition().x, head.getPosition().y - 8);
body.setPosition(head_old_position_x, head_old_position_y);
}

if (sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
{
head.setPosition(head.getPosition().x + 8, head.getPosition().y);
body.setPosition(head_old_position_x, head_old_position_y);
}

if (sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
{
head.setPosition(head.getPosition().x, head.getPosition().y + 8);
body.setPosition(head_old_position_x, head_old_position_y);
}

if (body.getPosition().x == candy.getPosition().x && body.getPosition().y == candy.getPosition().y)
{
score ++;
score_display.setString(std::to_string(score));
}

// REFRESH WINDOW
window.clear();
window.draw(background);
window.draw(head);
window.draw(body);
window.draw(poison);
window.draw(trap);
window.draw(candy);
window.draw(score_display);
window.display();
}
}

return 0;
}
ore_display.setString(std::to_string(score));
score_display.setPosition(5, 5);

// LOOP
while (window.isOpen())
{
sf::Event event;
while ( window.pollEvent(event))
{
if (event.type == sf::Event::Closed)
{ window.close(); }

head_old_position_x = head.getPosition().x;
head_old_position_y = head.getPosition().y;

// MOVEMENT BASED ON KEYBOARD INPUT
if (sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
{
head.setPosition(head.getPosition().x - 8, head.getPosition().y);
body.setPosition(head_old_position_x, head_old_position_y);
}

if (sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
{
head.setPosition(head.getPosition().x, head.getPosition().y - 8);
body.setPosition(head_old_position_x, head_old_position_y);
}

if (sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
{
head.setPosition(head.getPosition().x + 8, head.getPosition().y);
body.setPosition(head_old_position_x, head_old_position_y);
}

if (sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
{
head.setPosition(head.getPosition().x, head.getPosition().y + 8);
body.setPosition(head_old_position_x, head_old_position_y);
}

if (body.getPosition().x == candy.getPosition().x && body.getPosition().y == candy.getPosition().y)
{
score ++;
score_display.setString(std::to_string(score));
}

// REFRESH WINDOW
window.clear();
window.draw(background);
window.draw(head);
window.draw(body);
window.draw(poison);
window.draw(trap);
window.draw(candy);
window.draw(score_display);
window.display();
}
}

return 0;
}

相关讨论

好吧，我想我已经知道了。

可能未显示任何内容，因为事件循环中包含所有绘图内容

尝试将这些内容放入while(window.isOpen())循环范围。

相关讨论

您已经丢失了对纹理的引用。在您的情况下，纹理是load_img()函数中的局部变量。

在任何sprite使用它时，应保持纹理加载并可用。

我建议您阅读SFML教程的这一部分，其中解释了此问题。

相关讨论

您的纹理超出范围，请参阅对象何时"超出范围"？更多细节。您可以在load_img函数中声明纹理，但是在退出load_img并返回sprite之后，将删除sf::Texture t;。

因此这是一个更新的函数，您可以在其中将纹理存储在load_img函数之外，并通过引用将其传递。仅显示相关部分。首先，将纹理传递给load_img函数。删除sf::Texture t;。

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sf::Sprite load_img(std::string path, long x, long y, long w, long h, sf::Texture& t)
{
bool id = t.loadFromFile(path);
[...]
}

声明纹理并将其传递给load_img函数。

1 2	sf::Texture headtexture; sf::Sprite head = load_img(wdir +"img/head.png", 47, 39, 8, 8, headtexture);

如果对所有sprite进行此操作，它将起作用并正确显示图像/sprite。

编辑2017年9月25日

根据评论，这是一个不带功能的最小工作示例：

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相关讨论