我正在使用libGDX、Tiled Map和Box2D制作一个平台游戏。我想应用一些着色器。
我想要一个呈现在英雄身上的晕影效果。对于晕影效果,我使用了这个教程。 我遇到的问题是:如果相机是固定的,我可以得到我想要的效果。晕影效果会贴在英雄身上。但是,如果相机移动,这在滚动平台游戏中经常发生,晕影效果就不会贴在英雄身上。
看来我需要考虑相机位置来计算晕影效果的坐标,但我不知道该怎么做。 以下是我用于晕影效果的片段着色器:
varying vec4 v_color;
varying vec2 v_texCoord0;
uniform vec2 u_resolution;
uniform float u_PosX, u_PosY;
uniform sampler2D u_sampler2D;
const float outerRadius = 10, innerRadius = 1, intensity = .5;
void main(){
vec4 color = texture2D(u_sampler2D, v_texCoord0) * v_color;
vec2 relativePosition = gl_FragCoord.xy / u_resolution - vec2(u_PosX, u_PosY); //Position of the vignette
relativePosition.x *= u_resolution.x / u_resolution.y; //The vignette is a circle
float len = length(relativePosition);
float vignette = smoothstep(outerRadius, innerRadius, len);
color.rgb = mix(color.rgb, color.rgb * vignette, intensity);
gl_FragColor = color;
}
在游戏屏幕中,相关的代码为:public TestScreen(final MyGdxGame gam){
camera = new MyCamera();
camera.setToOrtho(false, width, height);
camera.update();
vertexShader = Gdx.files.internal("Shaders/vVignette.glsl").readString();
fragmentShader = Gdx.files.internal("Shaders/fVignette.glsl").readString();
shaderProgram = new ShaderProgram(vertexShader,fragmentShader);
shaderProgram.begin();
shaderProgram.setUniformf("u_resolution", camera.viewportWidth, camera.viewportHeight);
shaderProgram.end();
}
public void render(float delta) {
Gdx.gl.glClearColor(0.1f,0.1f,0.1f,1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
camera.update();
//calculation of the position of the effect depending on the position of the hero
posX = (Gdx.graphics.getWidth()/camera.viewportWidth) * hero.bodyHero.getPosition().x/camera.viewportWidth;
posY = (Gdx.graphics.getHeight()/camera.viewportHeight) * hero.bodyHero.getPosition().y/camera.viewportHeight;
shaderProgram.begin();
shaderProgram.setUniformf("u_PosX", posX);
shaderProgram.setUniformf("u_PosY", posY);
shaderProgram.end();
}
正如我所说,如果相机不移动,这段代码完美运行。但是由于相机移动时无法正常工作,我认为问题与相机投影有关,并在render()中尝试了这段代码,但仍然没有更好的结果。
Vector3 PosHero = new Vector3();
PosHero.set(hero.bodyHero.getPosition().x, hero.bodyHero.getPosition().y, 0);
camera.unproject(PosHero);
posX = (Gdx.graphics.getWidth()/camera.viewportWidth) * PosHero.x/camera.viewportWidth;
posY = (Gdx.graphics.getHeight()/camera.viewportHeight) * PosHero.y/camera.viewportHeight;
shaderProgram.begin();
shaderProgram.setUniformf("u_PosX", posX);
shaderProgram.setUniformf("u_PosY", posY);
shaderProgram.end();