增加rotatematrix.cpp范例

CMakeLists.txt

@@ -60,6 +60,7 @@ cm_example_project("DataType" IDNameTest            datatype/IDNameTest.cpp)
 ####################################################################################################
 cm_example_project("Math" OutputEpsilon         math/OutputEpsilon.cpp)
 cm_example_project("Math" TransformBenchmark    math/TransformBenchmark.cpp)
+cm_example_project("Math" RotateMatrix          math/RotateMatrix.cpp)
 
 ####################################################################################################
 cm_example_project("DataType/Collection" LifetimeTest    datatype/collection/LifetimeTest.cpp)

math/RotateMatrix.cpp

@@ -0,0 +1,39 @@
+#include<glm/glm.hpp>
+#include<glm/gtx/quaternion.hpp>
+#include<iostream>
+
+void PrintMatrix(const char *name,const glm::mat4 &m)
+{
+    std::cout<<"Matrix:"<<name<<"\n";
+    for(int i=0;i<4;i++)
+    {
+        for(int j=0;j<4;j++)
+            std::cout<<m[i][j]<<" ";
+        std::cout<<"\n";
+    }
+    std::cout<<"\n";
+}
+
+int main(int,char **)
+{
+    const glm::vec3   rotate_axis(0.0f,1.0f,0.0f); // Y-axis
+    const float       rotate_radians=glm::radians(90.0f);
+
+    glm::quat q =glm::angleAxis(rotate_radians,rotate_axis);
+    glm::mat4 m1=glm::toMat4(q);
+
+    glm::mat4 m2=glm::rotate(glm::mat4(1.0f),rotate_radians,rotate_axis);
+
+    float cos90=glm::cos(rotate_radians);
+    float acos90_1=glm::acos(cos90);
+    float acos90_2=glm::acos(5.96046e-08);
+
+    //m1方法结果是5.96046e-08
+    //m2方法结果是-4.37114e-08
+    //但其实它们结果是一样的，都是近似于0的数值。
+
+    PrintMatrix("From Quaternion",m1);
+    PrintMatrix("From Rotate",m2);
+
+    return 0;
+}