问题描述
我正在使用JavaFX制作类，并且试图将渐变应用于球体，但是(很明显)，我不知道该怎么做.我之所以陷入困境是因为我知道球体是一个物体，因此它需要一种材料，但是(就颜色而言)，PhongMaterial仅采用一种颜色，因此不会采用渐变，因为渐变是一种颜色范围.所以基本上我想做的是以下事情:
I'm working in JavaFX for a class, and I'm trying to apply a gradient to a sphere, but (obviously), I can't figure out how to do it. I'm stuck because I know that a sphere is an object, and so it needs to have a material, but (as far as colors go), a PhongMaterial only takes one color, and so it won't take a gradient because a gradient is a range of colors. So basically what I'm trying to is the following:
Sphere sphere = new Sphere(50);
RadialGradient rg = new RadialGradient(0, 0, 0, 0, 5, true, CycleMethod.REPEAT, /*arbitrary/irrelevant color Stop objects*/));
PhongMaterial pm = new PhongMaterial();
pm.setDiffuseMap(pm);
sphere.setMaterial(asdf);
现在显然该代码不起作用，但我想这就是我要尝试执行的操作的想法/流程.
Now obviously this code doesn't work, but I guess it's the idea/flow of what I'm trying to do.
推荐答案
您对一件事是正确的，PhongMaterial将Color用作漫反射颜色，而不允许使用Gradient.为此，它应该接受Paint，但事实并非如此.
You are right about one thing, PhongMaterial takes a Color as diffuse color, and that doesn't allow a Gradient. For that, it should accept Paint, but that is not the case.
所以我们必须寻找不同的选择.
So we have to look for different alternatives.
DiffuseMap
如果选中PhongMaterial，则可以设置漫反射贴图与图片.这意味着您可以使用具有一定梯度的现有图像并将其应用于球体.
If you check PhongMaterial, you can set the diffuse map with an image. That means that you can use an existing image with some gradient and apply it to the sphere.
类似这样的东西:
Sphere sphere = new Sphere(100);
PhongMaterial material = new PhongMaterial();
material.setDiffuseMap(new Image("http://westciv.com/images/wdblogs/radialgradients/simpleclorstops.png"));
sphere.setMaterial(material);
将产生以下结果:
动态DiffuseMap
显然，这具有依赖静态图像的缺点.如果要动态修改该怎么办?
Obviously, this has the disadvantage of depending on a static image. What if you want to modify that dynamically?
如果生成径向渐变，则可以执行此操作，将其渲染到辅助场景上并对其进行快照.此快照返回WritableImage，您可以直接将其用作漫反射贴图.
You can do that, if you generate your radial gradient, render it on a secondary scene and take a snapshot of it. This snapshot returns a WritableImage that you can use directly as diffuse map.
类似这样的东西:
Scene aux = new Scene(new StackPane(), 100, 100,
new RadialGradient(0, 0, 0.5, 0.5, 1, true, CycleMethod.REPEAT,
new Stop(0, Color.GREEN), new Stop(0.4, Color.YELLOW),
new Stop(0.6, Color.BLUE), new Stop(0.7, Color.RED)));
WritableImage snapshot = aux.snapshot(null);
Sphere sphere = new Sphere(100);
PhongMaterial material = new PhongMaterial();
material.setDiffuseMap(snapshot);
sphere.setMaterial(material);
您现在将拥有:
密度图
还有另一种使用数学函数生成密度图的选项，颜色将通过对该函数的映射来给出.
There is still another option to use a mathematical function to generate a density map, and the colors will be given by a mapping to that function.
为此，您不能使用内置的Sphere，但是必须创建自己的TriangleMesh并使用纹理坐标，或者可以仅使用开源JavaFX 3D FXyz 库，其中包含许多不同的基元和纹理选项.
For that you can't use the built-in Sphere, but you have to either create your own TriangleMesh and play with the texture coordinates, or you can simply use FXyz, an open source JavaFX 3D library with a number of different primitives and texture options.
在这种情况下，您可以从Maven Central(org.fxyz3d:fxyz3d:0.3.0)获取库，使用SegmentedSphereMesh控件，然后选择纹理模式`Vertices3D:
For this case, you can get the library from Maven Central (org.fxyz3d:fxyz3d:0.3.0), use a SegmentedSphereMesh control, and then select the texture mode `Vertices3D:
SegmentedSphereMesh sphere = new SegmentedSphereMesh(100);
sphere.setTextureModeVertices3D(1530, p -> p.z);
请注意，这种情况下的功能仅基于z坐标，但是显然您可以根据需要进行修改.
Note the function in this case is just based on the z coordinate, but obviously you can modify that as needed.
检查库(有一个采样器)，以探索其他选项.
Check the library (there is a sampler), to explore other options.
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