SFML着色器不工作

Question

我试图单击时，他们创建一个轮廓效果，我的按钮，但ATM我只是测试的东西着色器......每当我画的东西与我的着色寿它呈现的形状完全黑

#include <SFML\Graphics.hpp> 

int main(){ 
    sf::RenderWindow window(sf::VideoMode(500, 500), "hello world", sf::Style::Close); 

    sf::RectangleShape rect; 
    rect.setSize(sf::Vector2f(100, 100)); 
    rect.setFillColor(sf::Color::Red); 

    sf::Shader blur; 
    if (!blur.loadFromFile("blur.frag", sf::Shader::Fragment)){ 
     return 1; 
    } 
    if (!blur.isAvailable()){ 
     return 1; 
    } 
    blur.setUniform("texture", sf::Shader::CurrentTexture); 
    blur.setUniform("blur_radius", 0.002f); 

    while (window.isOpen()){ 

     sf::Event evnt; 

     while (window.pollEvent(evnt)){ 
      if (evnt.type == sf::Event::Closed) 
       window.close(); 
     } 

     window.clear(sf::Color(0, 100, 100)); 

     sf::RenderStates state; 
     state.shader = &blur; 
     window.draw(rect, state); 

     window.display(); 
    } 
    return 0; 
} 

和我的着色器代码。

uniform sampler2D texture; 
uniform float blur_radius; 

void main() 
{ 
    vec2 offx = vec2(blur_radius, 0.0); 
    vec2 offy = vec2(0.0, blur_radius); 

    vec4 pixel = texture2D(texture, gl_TexCoord[0].xy)    * 4.0 + 
       texture2D(texture, gl_TexCoord[0].xy - offx)  * 2.0 + 
       texture2D(texture, gl_TexCoord[0].xy + offx)  * 2.0 + 
       texture2D(texture, gl_TexCoord[0].xy - offy)  * 2.0 + 
       texture2D(texture, gl_TexCoord[0].xy + offy)  * 2.0 + 
       texture2D(texture, gl_TexCoord[0].xy - offx - offy) * 1.0 + 
       texture2D(texture, gl_TexCoord[0].xy - offx + offy) * 1.0 + 
       texture2D(texture, gl_TexCoord[0].xy + offx - offy) * 1.0 + 
       texture2D(texture, gl_TexCoord[0].xy + offx + offy) * 1.0; 

    gl_FragColor = gl_Color * (pixel/16.0); 
} 

我期望一个模糊的红色矩形出现在左上角的圆角，而不是一个黑色的实心矩形。

Answer 1

因为rect没有纹理附加到它，在blur.frag使用的所有像素都无效，我想在这种情况下，用黑色的像素，因此黑色矩形。

你应该create a texture（使用sf::RenderTexture），绘制任何你想要的，然后在它上面创建一个sf::Sprite并绘制这个精灵。或者，您可以加载纹理from an image。

#include <SFML/Graphics.hpp> 

int main(){ 
    sf::RenderWindow window(sf::VideoMode(200, 200), "hello world", sf::Style::Close); 
    window.setFramerateLimit(60); 

    sf::RectangleShape rectBlue; 
    rectBlue.setSize(sf::Vector2f(100, 50)); 
    rectBlue.setFillColor(sf::Color::Blue); 
    sf::RectangleShape rectYellow; 
    rectYellow.setSize(sf::Vector2f(100, 50)); 
    rectYellow.setFillColor(sf::Color::Yellow); 
    rectYellow.setPosition(0, 50); 

    sf::RenderTexture renderTexture; 
    if (!renderTexture.create(100, 100)){ //create a render texture 
     return 1; 
    } 
    renderTexture.clear(); 
    renderTexture.draw(rectBlue); //draw blue rect on the render texture 
    renderTexture.draw(rectYellow); //draw yellow rect 
    renderTexture.display(); 
    sf::Sprite sprite(renderTexture.getTexture()); //create a sprite from the created texture 

    sf::Shader blur; 
    if (!blur.loadFromFile("blur.frag", sf::Shader::Fragment)){ 
     return 1; 
    } 
    if (!blur.isAvailable()){ 
     return 1; 
    } 
    blur.setUniform("texture", sf::Shader::CurrentTexture); 
    blur.setUniform("blur_radius", 0.05f); 

    while (window.isOpen()){ 

     sf::Event evnt; 

     while (window.pollEvent(evnt)){ 
      if (evnt.type == sf::Event::Closed) 
       window.close(); 
     } 

     window.clear(sf::Color(0, 100, 100)); 
     window.draw(sprite, &blur); //draw the sprite with blur shader 
     window.display(); 
    } 
    return 0; 
} 

结果：