在画布上绘制两个3D字符串？ [英] Drawing two 3D strings on Canvas?

问题描述

我必须在canvas上绘制2个字符串。字符必须用相同的坐标来绘制，第二个字符串必须是第一个字符串绕轴Y旋转45度的结果。结果必须如下所示：

I have to draw 2 Strings on canvas.Strings must be drawn with the same coordinates and second string must be result of rotating first string 45 degrees around axis Y.The result must looks like this:

>

这是我的代码：

Matrix matrix = new Matrix();
matrix = canvas.getMatrix();
mCamera = new Camera();


canvas.drawText("In the name of God", 30, 100, redPaint);
mCamera.rotateY(45);
mCamera.getMatrix(matrix);

matrix.preTranslate(30, 100);
//      matrix.postTranslate(-30, -100);

canvas.setMatrix(matrix);
canvas.drawText("In the name of God", 0, 0, greenPaint);

但上述代码的结果是：

您可以看到字符串的坐标是不同的。我做错了什么？我想这是由 matrix.preTranslate（）的不正确的参数引起的。

You can see that coordinates of strings are different.So what did I do wrong?I guess that it is be caused by incorrect arguments for matrix.preTranslate().

更新：

我更改我的代码：

canvas.drawText("In the name of God", 30, 100, redPaint);
mCamera.rotateY(45);
mCamera.getMatrix(matrix);
matrix.preTranslate(-30, -100);
matrix.postTranslate(30, 100);
canvas.setMatrix(matrix);
canvas.drawText("In the name of God", 0, 0, greenPaint);

或类似：

canvas.drawText("In the name of God", 30, 100, redPaint);
mCamera.rotateY(45);
mCamera.getMatrix(matrix);
matrix.preTranslate(-30, -100);
//matrix.postTranslate(30, 100);
canvas.setMatrix(matrix);
canvas.drawText("In the name of God", 0, 0, greenPaint);

或类似：

canvas.drawText("In the name of God", 30, 100, redPaint);
mCamera.rotateY(45);
mCamera.getMatrix(matrix);

matrix.preTranslate(-30, -100);
//      matrix.postTranslate(30, 100);
canvas.setMatrix(matrix);
canvas.drawText("In the name of God", 30, 100, greenPaint);

对于上述三个代码，结果如下：

And for all three above codes, result looks like this:

>

我想第二个文本超出范围或在状态栏后面，因此它不可见。

I guess that second text is drawn out of range or behind the status bar and so it is not visible.

然后将我的代码更改为：

Then change my code to:

mCamera.rotateY(45);
mCamera.getMatrix(matrix);
matrix.preTranslate(-30, -100);
matrix.postTranslate(30, 100);
canvas.setMatrix(matrix);
canvas.drawText("In the name of God", 30, 100, greenPaint);

结果：

推荐答案

感谢回复。我解决了问题。我必须使用 canvas.concat（）而不是 canvas.setMatrix 。这是正确的代码：

Thanks for replies.I solved the problem.I have to use canvas.concat() instead of canvas.setMatrix.This is correct code:

Matrix matrix = new Matrix();
mCamera = new Camera();

canvas.drawText("In the name of God", 30, 100, redPaint);
mCamera.rotateY(60);
mCamera.getMatrix(matrix);

matrix.preTranslate(-30, -100);
matrix.postTranslate(30, 100);
canvas.concat(matrix);
canvas.drawText("In the name of God", 30, 100, greenPaint);

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