[英]OpenGL projection matrix for perspective with fovy and aspect
I'm making my custom frustum
and perspective
implementations, part of the reasons are that I might need to do it myself, without library, in the future, and I want to polish up computer graphics skills before the exam. 我正在制作我的自定义视frustum
和perspective
实现,部分原因是我可能需要自己做,没有库,将来,我想在考试之前提高计算机图形技能。
I'm following a book and I am converting their examples in C++ to my ones in Java/LWJGL, however one example strikes me, it is the projection of a cube. 我正在关注一本书,我正在用C ++将它们的例子转换成我在Java / LWJGL中的例子,但是一个例子让我感到震惊,它是一个立方体的投影。
My cube is projected much further away (about double?) as theirs, which is odd. 我的立方体被投射得更远(大约两倍?),因为它们很奇怪。
This are my implemenations in column-major order: 这是我在列主要顺序中的实现:
public static Matrix4f frustum(final float left, final float right, final float bottom, final float top, final float near, final float far) {
return new Matrix4f(new float[] {
2 * near / (right - left), 0.0f, 0.0f, 0.0f, //X column
0.0f, 2 * near / (top - bottom), 0.0f, 0.0f, //Y column
(right + left) / (right - left), (top + bottom) / (top - bottom), (near + far) / (near - far), -1.0f, //Z column
0.0f, 0.0f, 2 * near * far / (near - far), 0.0f //Z column
});
}
public static Matrix4f perspective(final float fovy, final float aspect, final float near, final float far) {
float y2 = near * (float)Math.tan(Math.toRadians(fovy));
float y1 = -y2;
float x1 = y1 * aspect;
float x2 = y2 * aspect;
return frustum(x1, x2, y1, y2, near, far);
}
I've seen somewhere where they use a similar y2
as I have but divide it by 2, however I do not want to make a dirty fix without exactly understanding why it is going wrong. 我已经看到过他们使用类似y2
地方,但除以2,但是我不想在没有完全理解为什么会出错的情况下进行肮脏的修复。
Could someone verify whether the perspective
matrix I am using, and point me out what the other reasons could be that my object looks to be further away? 有人可以验证我正在使用的perspective
矩阵,并指出我的对象看起来更远的其他原因是什么?
I have got my other matrix math right and I am only translating the cube by (0f, 0f, -4f)
and verified that that was also correct. 我有其他矩阵数学正确,我只是通过(0f, 0f, -4f)
翻译立方体并验证这也是正确的。
Would a wrongly implemented perspective
matrix cause my object to be further away? 错误实现的perspective
矩阵会导致我的对象更远吗?
Your implementation of frustum seems correct. 你对frustum的实现似乎是正确的。
In your implementation of perspective, fovy should be fovy / 2 instead. 在你的透视实现中,fovy应该是fovy / 2。
See this answer: https://stackoverflow.com/a/21064935/3146587 请参阅此答案: https : //stackoverflow.com/a/21064935/3146587
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