glm 在简单翻译上返回 nan

问题描述

我正在使用 glfw、glad 和 glm 修补 OpenGL.在我使用的其中一个教程中，他们演示了 glm 的一些简单用法:

I'm tinkering with OpenGL using glfw, glad, and glm. In one of the tutorials I'm using, they demonstrate some simple usage of glm as so:

glm::vec4 vec(1.0f, 0.0f, 0.0f, 1.0f);
glm::mat4 trans;
trans = glm::translate(trans, glm::vec3(1.0f, 1.0f, 0.0f));
vec = trans * vec;
std::cout << vec.x << vec.y << vec.z << std::endl;

当我编译并运行这段代码时，我得到了垃圾值(通常是 NAN).教程特别指出，实例化

When I compile and run this code, I get trash values (usually NAN). The tutorial specifically noted that instantiating

glm::mat4 trans;

默认情况下会为变量trans"创建一个单位矩阵.我想也许这就是问题所在，尽管我已经确认 glm 默认情况下会这样做.

would by default create an identity matrix for the varialbe "trans". I'm thinking that perhaps this is the issue, though I have verified that glm does do this by default.

如果有帮助，您可以找到整个源文件 在这里在第 308 行.非常感谢您的时间！

In case it would be helpful, you can find the entire source file here on line 308. I greatly appreciate your time!

推荐答案

你必须初始化矩阵变量 glm::mat4 trans.

You have to initialize the matrix variable glm::mat4 trans.

glm API 文档是指OpenGL 着色语言规范 4.20.

5.4.2 向量和矩阵构造函数

如果向量构造函数只有一个标量参数，则它用于将构造向量的所有组件初始化为该标量的值.如果矩阵构造函数只有一个标量参数，它用于初始化矩阵对角线上的所有分量，其余分量初始化为 0.0.

If there is a single scalar parameter to a vector constructor, it is used to initialize all components of the constructed vector to that scalar’s value. If there is a single scalar parameter to a matrix constructor, it is used to initialize all the components on the matrix’s diagonal, with the remaining components initialized to 0.0.

这意味着，可以通过单个参数 1.0 初始化单位矩阵:glm::mat4(1.0f).

This means, that an identity matrix can be initialized by the single parameter 1.0: glm::mat4(1.0f).

像这样改变你的代码:

glm::mat4 trans(1.0f);

另请参阅 OpenGL 数学 (GLM)；2. 向量和矩阵构造器

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