我想实现一个二维水面算法,描述在这里和这里。但是,我不想使用两个int数组并在CPU上计算,我想使用SFML的
到目前为止,我已经取得了一些进展。我能够正确地设置3个
请记住,这一切只涉及高度场的创建。目前还没有对水进行着色。
你知道为什么波浪会自动消失而不衰减吗?
sf::RenderTexture
(基本上是FBO)和GLSL着色器在GPU上运行所有内容。我想使用SFML,因为它非常简单,而且我之前已经使用过它,所以我对它有一定了解。到目前为止,我已经取得了一些进展。我能够正确地设置3个
sf::RenderTextures
并在它们之间进行ping-pong(因为除了int数组之外,您不能同时读写同一个sf::RenderTexture
)。我还能够将高度场创建算法从范围-32.767到32.767适应到范围0到1(或更准确地说是-0.5到0.5进行计算)。添加新的涟漪也可以在某种程度上起作用。所以到这一点上,你实际上可以看到一些波浪。
现在出现了我的问题:波浪消失得非常快,即使我还没有施加任何阻尼。根据算法,如果没有施加阻尼,涟漪不会停止。甚至恰恰相反。如果我施加“放大”,波浪看起来接近您期望的样子(但它们仍然会在没有施加任何阻尼的情况下消失)。我的第一个想法是,这是因为我使用的是0-1范围内的浮点数,而不是整数,但我只看到这在使用乘法时会成为问题,但我只使用加法和减法。
以下是我的SFML C++代码:
#include <SFML/Graphics.hpp>
#include <iostream>
int main()
{
sf::RenderWindow window(sf::VideoMode(1000, 1000), "SFML works!");
window.setFramerateLimit(12);
sf::RenderTexture buffers[3];
buffers[0].create(500, 500);
buffers[1].create(500, 500);
buffers[2].create(500, 500);
sf::RenderTexture* firstBuffer = buffers;
sf::RenderTexture* secondBuffer = &buffers[1];
sf::RenderTexture* finalBuffer = &buffers[2];
firstBuffer->clear(sf::Color(128, 128, 128));
secondBuffer->clear(sf::Color(128, 128, 128));
finalBuffer->clear(sf::Color(128, 128, 128));
sf::Shader waterHeightmapShader;
waterHeightmapShader.loadFromFile("waterHeightmapShader.glsl", sf::Shader::Fragment);
sf::Sprite spritefirst;
spritefirst.setPosition(0, 0);
spritefirst.setTexture(firstBuffer->getTexture());
sf::Sprite spritesecond;
spritesecond.setPosition(500, 0);
spritesecond.setTexture(secondBuffer->getTexture());
sf::Sprite spritefinal;
spritefinal.setPosition(0, 500);
spritefinal.setTexture(finalBuffer->getTexture());
while (window.isOpen())
{
sf::Event event;
while (window.pollEvent(event))
{
if(event.type == sf::Event::Closed)
window.close();
if(event.type == sf::Event::KeyReleased && event.key.code == sf::Keyboard::Escape)
window.close();
}
waterHeightmapShader.setParameter("mousePosition", sf::Vector2f(-1.f, -1.f));
// if mouse button is pressed add new ripples
if(sf::Mouse::isButtonPressed(sf::Mouse::Left))
{
sf::Vector2i mousePosition = sf::Mouse::getPosition(window);
if(mousePosition.x < 500 && mousePosition.y < 500)
{
sf::Vector2f mouse(mousePosition);
mouse.x /= 500.f;
mouse.y /= 500.f;
mouse.y = 1 - mouse.y;
std::cout << mouse.x << " " << mouse.y << std::endl;
waterHeightmapShader.setParameter("mousePosition", mouse);
}
}
waterHeightmapShader.setParameter("textureTwoFramesAgo", firstBuffer->getTexture());
waterHeightmapShader.setParameter("textureOneFrameAgo", secondBuffer->getTexture());
// create the heightmap
secondBuffer->display();
finalBuffer->clear(sf::Color(128, 128, 128));
finalBuffer->draw(sf::Sprite(secondBuffer->getTexture()), &waterHeightmapShader);
finalBuffer->display();
spritefirst.setTexture(firstBuffer->getTexture());
spritesecond.setTexture(secondBuffer->getTexture());
spritefinal.setTexture(finalBuffer->getTexture());
window.clear();
window.draw(spritefirst);
window.draw(spritesecond);
window.draw(spritefinal);
window.display();
// swap the buffers around, first becomes second, second becomes third and third becomes first
sf::RenderTexture* swapper = firstBuffer;
firstBuffer = secondBuffer;
secondBuffer = finalBuffer;
finalBuffer = swapper;
}
return 0;
}
这是我的GLSL着色器代码:
uniform sampler2D textureTwoFramesAgo;
uniform sampler2D textureOneFrameAgo;
uniform vec2 mousePosition;
const float textureSize = 500.0;
const float pixelSize = 1.0 / textureSize;
void main()
{
// pixels position
vec2 position = gl_TexCoord[0].st;
vec4 finalColor = ((texture2D(textureOneFrameAgo, vec2(position.x - pixelSize, position.y)) +
texture2D(textureOneFrameAgo, vec2(position.x + pixelSize, position.y)) +
texture2D(textureOneFrameAgo, vec2(position.x, position.y + pixelSize)) +
texture2D(textureOneFrameAgo, vec2(position.x, position.y - pixelSize)) - 2.0) / 2) -
(texture2D(textureTwoFramesAgo, position) - 0.5);
// damping
// finalColor.rgb *= 1.9; // <---- uncomment this for the "amplifiction" ie. to see the waves better
finalColor.rgb += 0.5;
// add new ripples
if(mousePosition.x > 0.0)
{
if(distance(position, mousePosition) < pixelSize * 5)
{
finalColor = vec4(0.9, 0.9, 0.9, 1.0);
}
}
gl_FragColor = finalColor;
}
请记住,这一切只涉及高度场的创建。目前还没有对水进行着色。
你知道为什么波浪会自动消失而不衰减吗?