我试图将一些具有透明度的图形渲染到WebGLRenderTarget中。然后将渲染图像用作第二材料的纹理。
我有alpha混音的问题。我在alpha = 0.5时获得的颜色比预期的颜色更深。
下图显示了问题:
我认为我错过了一些东西!
部分代码报告如下。您可以在以下jsbin中找到完整的代码:https://jsbin.com/zukoyaziqe/1/edit?html,js,output
感谢您的帮助!!
着色器:
const texFrag = `
varying vec2 vUv;
void main() {
vec2 center = vec2(0.5, 0.2);
float d = length(vUv - center);
if (d < 0.1) {
gl_FragColor = vec4(1.0,0.0,1.0,0.5);
}
else {
discard;
}
}
`;
质地:
const makeTexture = (renderer, width, height) => {
const target = new THREE.WebGLRenderTarget(width, height, {minFilter: THREE.LinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBAFormat, type: THREE.FloatType});
const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(90, 1, 0.1, 100000);
const geometry = new THREE.PlaneGeometry(2, 2);
const material = new THREE.ShaderMaterial({
transparent : true,
vertexShader : simpleVert,
fragmentShader : texFrag,
});
const mesh = new THREE.Mesh(geometry, material);
camera.position.set(0, 0, 1);
scene.add(camera);
scene.add(mesh);
renderer.render(scene, camera, target, true);
return target.texture;
}
主要观点:
const renderer = new THREE.WebGLRenderer({canvas});
const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(90, 1, 0.1, 100000);
const geometry = new THREE.PlaneGeometry( 2, 2 );
const material = new THREE.MeshBasicMaterial({
transparent : true,
map : makeTexture(renderer, canvas.width, canvas.height)
});
const mesh = new THREE.Mesh(geometry, material);
答案 0 :(得分:1)
首先,在您链接的示例中,您的main函数被调用两次,因此有两个CSS圆圈堆叠在一起,导致圆圈不太透明。
然后,您在空白渲染目标上绘制一个颜色为(1,0,1,0.5)的圆圈,使用默认混合模式(SRC_ALPHA,ONE_MINUS_SRC_ALPHA),得到(0.5,0, 0.5,0.5)颜色,然后用作纹理。如果要在纹理中使用原始颜色,则应禁用Alpha混合或使用其他混合模式。只需在transparent
内设置false
到makeTexture
即可。