Just in case anyone else is looking for code, this is what I found at about 1.30 in the morning (
https://github.com/SFML/SFML/wiki/Source%3A-Radial-Gradient-Shader, thanks Hapax).
It is as was but just changed setParameter to setUniform as it was deprecated.
#include <SFML/Graphics.hpp>
#include <iostream>
const char VertexShader[] =
"void main()"
"{"
"gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;"
"gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;"
"gl_FrontColor = gl_Color;"
"}";
const char RadialGradient[] =
"uniform vec4 color;"
"uniform vec2 center;"
"uniform float radius;"
"uniform float expand;"
"uniform float windowHeight;"
"void main(void)"
"{"
"vec2 centerFromSfml = vec2(center.x, windowHeight - center.y);"
"vec2 p = (gl_FragCoord.xy - centerFromSfml) / radius;"
"float r = sqrt(dot(p, p));"
"if (r < 1.0)"
"{"
"gl_FragColor = mix(color, gl_Color, (r - expand) / (1.0 - expand));"
"}"
"else"
"{"
"gl_FragColor = gl_Color;"
"}"
"}";
int main()
{
if (!sf::Shader::isAvailable())
{
std::cerr << "Shaders are not available." << std::endl;
return EXIT_FAILURE;
}
sf::RenderWindow window(sf::VideoMode(800, 600), "Radial Gradient", sf::Style::Default);
window.setFramerateLimit(30);
sf::CircleShape circle;
sf::RectangleShape rectangle;
sf::Shader shader;
circle.setRadius(50.f);
circle.setOrigin(circle.getRadius(), circle.getRadius());
circle.setPosition(sf::Vector2f(window.getSize()) / 2.f);
circle.setFillColor(sf::Color::Transparent);
rectangle.setSize({ 300.f, 200.f });
rectangle.setFillColor(sf::Color::Yellow);
rectangle.setOrigin(rectangle.getLocalBounds().width / 2.f, rectangle.getLocalBounds().height / 2.f);
rectangle.setPosition(sf::Vector2f(window.getSize()) / 4.f);
shader.loadFromMemory(VertexShader, RadialGradient);
shader.setUniform("windowHeight", static_cast<float>(window.getSize().y)); // this must be set, but only needs to be set once (or whenever the size of the window changes)
while (window.isOpen())
{
sf::Event event;
while (window.pollEvent(event))
{
if ((event.type == sf::Event::Closed) || (event.type == sf::Event::KeyPressed) || (event.key.code == sf::Keyboard::Escape))
window.close();
}
sf::Glsl::Vec4 tcolor = sf::Color::Red;
sf::Glsl::Vec4 tcolor2 = sf::Color::Blue;
window.clear();
shader.setUniform("color", tcolor);
shader.setUniform("center", rectangle.getPosition() + sf::Vector2f(0.f, 0.f));
shader.setUniform("radius", 200.f);
shader.setUniform("expand", 0.25f);
window.draw(rectangle, &shader);
shader.setUniform("color", tcolor2);
shader.setUniform("center", circle.getPosition());
shader.setUniform("radius", circle.getRadius());
shader.setUniform("expand", 0.f);
window.draw(circle, &shader);
window.display();
}
return EXIT_SUCCESS;
}
