SFML 2.0 GLSL体积光散射着色器

Question

使用Kenny Mitchell在GPU Gems 3中提供的GLSL着色器源代码，我尝试使用SFML 2.0创建一些2D神光线。目前，每当我编译和调试项目时，掩码纹理和精灵（分别为“image.png”和“精灵”）都会完全消失。我目前设置的项目非常粗糙，只包含一个main.cpp文件和着色器文件，但我觉得我需要的比现在更多。任何帮助将非常感激！源代码将在下面提供。

main.cpp中：

#include <SFML\Graphics.hpp>
#include <SFML\System.hpp>
#include <SFML\Window.hpp>
#include <iostream>

void main()
{
    sf::RenderWindow _window(sf::VideoMode(800, 480, 32), "Lighting Test");
    _window.setFramerateLimit(60);

    sf::Shader lightingShader;
    sf::RenderStates renderState;

    sf::Texture texture;
    texture.loadFromFile("image.png");

    sf::Sprite sprite;
    sprite.setTexture(texture);

    sf::Texture backgroundTexture;
    backgroundTexture.loadFromFile("light.png");

    sf::Sprite background;
    background.setTexture(backgroundTexture);

    while (_window.isOpen())
    {
        int x = sf::Mouse::getPosition(_window).x;
        int y = sf::Mouse::getPosition(_window).y;

        lightingShader.loadFromFile("lightingShader.vert", "lightingShader.frag");
        lightingShader.setParameter("exposure", 0.25f);
        lightingShader.setParameter("decay", 0.97f);
        lightingShader.setParameter("density", 0.97f);
        lightingShader.setParameter("weight", 0.5f);
        lightingShader.setParameter("lightPositionOnScreen", sf::Vector2f(0.5f, 0.5f));
        lightingShader.setParameter("myTexture", sf::Shader::CurrentTexture);
        renderState.shader = &lightingShader;

        _window.clear(sf::Color::Black);
        sprite.setPosition(x, y);
        //sprite.setColor(sf::Color::Black);
        //background.setPosition(400, 240);
        _window.draw(background);
        _window.draw(sprite, renderState);
        _window.display();
    }
}

lightingShader.vert：

void main() 
{

    gl_TexCoord[0] = gl_MultiTexCoord0;
    gl_Position = ftransform();
}

lightingShader.frag：

uniform float exposure;
uniform float decay;
uniform float density;
uniform float weight;
uniform vec2 lightPositionOnScreen;
uniform sampler2D myTexture;
const int NUM_SAMPLES = 100 ;
void main()
{   
    vec2 deltaTextCoord = vec2( gl_TexCoord[0].st - lightPositionOnScreen.xy );
    vec2 textCoord = gl_TexCoord[0].st;
    deltaTextCoord *= 1.0 /  float(NUM_SAMPLES) * density;
    float illuminationDecay = 1.0;


    for(int i=0; i < NUM_SAMPLES ; i++)
    {
            textCoord -= deltaTextCoord;
            vec4 sample = texture2D(myTexture, textCoord);

            sample *= illuminationDecay * weight;

            gl_FragColor += sample;

            illuminationDecay *= decay;
    }


    gl_FragColor *= exposure;
}

Answer 1

我终于自己解决了这个问题。原来我创建的顶点着色器是不必要的，我所要做的就是替换：

lightingShader.loadFromFile("lightingShader.vert", "lightingShader.frag");

附：

lightingShader.loadFromFile("lightingShader.frag", sf::Shader::Type::Fragment);。