[英]How to properly rotate and scale an object in OpenGL?
I'm trying to build the model matrix every frame, for that I'm creating a translation, rotation, and scale matrix and multiplying it. 我正在尝试每帧构建模型矩阵,为此我创建了平移,旋转和缩放矩阵并将其相乘。 But I can't seem to figure it how to build the rotation matrix and scale it properly.
但是我似乎无法弄清楚它如何构建旋转矩阵并正确缩放它。
Here's what I'm doing: 这是我在做什么:
glm::mat4 scale = glm::scale(mat4(1.0f), my_models[i].myscale);
glm::mat4 rotateM(1.0);
glm:mat4 translate = glm::translate(mat4(1.0f), my_models[i].initialPos);
rotateM = mat4_cast(my_models[i].Quat);
rotateM = glm::rotate(rotateM, (float) my_models[i].angle * t, my_models[i].animation_axis[0]);
my_models[i].modelMatrix = translate * rotateM *scale;
my_models[i].Quat = quat_cast(my_models[i].modelMatrix);
In the Constructor I'm using: 在构造函数中,我正在使用:
quat Quat = glm::angleAxis(glm::radians(90.f), glm::vec3(0.f, 1.f, 0.f));
If my_models[i].myscale exactly 1.0f it rotates just fine, but if it is bigger the object keeps growing and rotates weirdly. 如果my_models [i] .myscale恰好为1.0f,它旋转就很好,但是如果它更大,则对象将继续增长并怪异地旋转。 Quaternions are very new to me, so I'm assuming I'm messing up there.
四元数对我来说很新,所以我假设我在搞砸。
What am I missing? 我想念什么? Are there simpler ways to construct the models rotation matrix?
有没有更简单的方法来构建模型旋转矩阵? if so, what information should I be saving?
如果是这样,我应该保存什么信息?
Edit: As jparima suggested, the following fixed my problem. 编辑:正如jparima建议,以下解决了我的问题。
glm::mat4 scale = glm::scale(mat4(1.0f), my_models[i].myscale);
glm::mat4 rotateM(1.0);
glm::mat4 translate = glm::translate(mat4(1.0f), my_models[i].initialPos);
my_models[i].Quat = rotate(my_models[i].Quat, my_models[i].angle * t, my_models[i].animation_axis[0]);
rotateM = mat4_cast(my_models[i].Quat);
my_models[i].modelMatrix = translate * rotateM * scale;
From the GLM quaternion.hpp for quat_cast
it says 从GLM quaternion.hpp获得
quat_cast
它说
Converts a pure rotation 4 * 4 matrix to a quaternion.
将纯旋转4 * 4矩阵转换为四元数。
You are setting the whole model matrix there which has also scale and translation. 您要在那里设置整个模型矩阵,该矩阵也具有缩放和平移。 In fact, I don't know why you are converting a matrix to quaternion at all.
实际上,我根本不知道为什么要将矩阵转换为四元数。 Therefore you could remove the last line (
quat_cast
) and update the quaternion directly if you want to apply rotations. 因此,如果要应用旋转,则可以删除最后一行(
quat_cast
)并直接更新四元数。
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