问题描述
说明: 在我的程序中,我确实有一个对象,单击该对象将绘制3个旋转轴。通过单击其中一个轴并在周围移动鼠标,可以旋转对象。
问题:对象始终围绕局部轴旋转而不是围绕世界轴旋转,这会导致不良行为。 为了解决该问题,我尝试了this,但还是没有用。
代码: 当我加载对象时,我将其旋转以使其面向相机。
m_phantomRotationMatrix = glm::rotate(m_phantomRotationMatrix,-90 * glm::pi<float>() / 180.0f,glm::vec3(1.0f,0.0f,0.0f));
m_phantomRotationMatrix = glm::rotate(m_phantomRotationMatrix,90 * glm::pi<float>() / 180.0f,glm::vec3(0.0f,1.0f));
然后在事件处理程序中移动鼠标,如果移动鼠标,我将进一步旋转
case 5: // X rotation axis
{
GLfloat xCurrentPosition = wxGetMousePosition().x;
GLfloat yCurrentPosition = wxGetMousePosition().y;
m_phantomRotationMatrix = glm::rotate(m_phantomRotationMatrix,(xCurrentPosition - m_xLastPosition) * glm::pi<float>() / 180.0f,0.0f));
m_xLastPosition = xCurrentPosition;
m_yLastPosition = yCurrentPosition;
break;
}
case 6: // Y rotation axis
{
GLfloat xCurrentPosition = wxGetMousePosition().x;
GLfloat yCurrentPosition = wxGetMousePosition().y;
m_phantomRotationMatrix = glm::rotate(m_phantomRotationMatrix,(yCurrentPosition - m_yLastPosition) * glm::pi<float>() / 180.0f,1.0f,0.0f));
m_xLastPosition = xCurrentPosition;
m_yLastPosition = yCurrentPosition;
break;
}
case 7: // Z rotation axis
{
GLfloat xCurrentPosition = wxGetMousePosition().x;
GLfloat yCurrentPosition = wxGetMousePosition().y;
m_phantomRotationMatrix = glm::rotate(m_phantomRotationMatrix,1.0f));
m_xLastPosition = xCurrentPosition;
m_yLastPosition = yCurrentPosition;
break;
}
主循环
void MyGLCanvas::draw(wxDC& dc)
{
wxGLCanvas::SetCurrent(*m_glContext);
glEnable(GL_MULTISAMPLE);
glViewport(0,m_windowWidth,m_windowHeight);
glEnable(GL_DEPTH_TEST);
glEnable(GL_STENCIL_TEST);
glClearDepth(1.0f);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
glDepthFunc(GL_LEQUAL);
m_rotationAngleAroundPhantom++;
glm::mat4 phantomModel,view,projection;
phantomModel = glm::translate(phantomModel,m_phantomPosition);
view = m_fpsCamera->getViewMatrix();
projection = m_fpsCamera->getProjectionMatrix(m_windowWidth,m_windowHeight);
m_color = glm::vec4(0.310f,0.747f,0.185f,1.0f);
glm::vec3 lightPos = glm::vec3(0.0f,0.0f);
glm::vec3 lightColor = glm::vec3(1.0f,1.0f);
ShaderProgram shaderProgram;
shaderProgram.loadShaders("Shaders/phantom.vert","Shaders/phantom.frag");
glClearStencil(0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
shaderProgram.use();
shaderProgram.setUniform("phantomRotationMatrix",m_phantomRotationMatrix);
shaderProgram.setUniform("model",phantomModel);
shaderProgram.setUniform("view",view);
shaderProgram.setUniform("projection",projection);
shaderProgram.setUniform("color",m_color);
shaderProgram.setUniform("lightColor",lightColor);
shaderProgram.setUniform("lightPos",m_fpsCamera->getPosition());
shaderProgram.setUniform("cameraPos",m_fpsCamera->getPosition());
glStencilMask(0xFF); // Write to stencil buffer
glStencilOp(GL_KEEP,GL_KEEP,GL_REPLACE);
glStencilFunc(GL_ALWAYS,0xFF); // Set any stencil to 0
glStencilFunc(GL_ALWAYS,1,0xFF); // Set any stencil to object ID
m_pantomMesh->draw();
glStencilFunc(GL_ALWAYS,0xFF); // Set any stencil to 0
shaderProgram.deleteProgram();
if (phantomIsSelected && leftMouseClicked)
{
drawMovementAxes(phantomModel,projection);
}
if (phantomIsSelected && rightMouseClicked)
{
drawRotationAxes(phantomModel,projection);
}
glFlush();
wxGLCanvas::SwapBuffers();
}
顶点着色器
#version 330 core
layout (location = 0) in vec3 pos;
layout (location = 1) in vec3 normal;
out vec4 vert_color;
out vec3 Normal;
out vec3 FragPos;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
uniform mat4 phantomRotationMatrix;
uniform vec4 color;
void main()
{
vert_color = color;
gl_Position = projection * view * model * phantomRotationMatrix * vec4(pos.x,pos.y,pos.z,1.0);
FragPos = vec3(model * phantomRotationMatrix * vec4(pos,1.0));
Normal = vec3(transpose(inverse(phantomRotationMatrix)) * vec4(normal,0.0));
}
解决方法
您具有模型视图矩阵(实际上,它在着色器中),但是您可以在CPU中对其进行完全相同的计算。您只需要将旋转矩阵的倒数与模型矩阵相乘即可获得对象空间中的旋转,然后将其相乘/应用于您的对象。
如果我正确理解您的代码,那么您或多或少会这样做:
World = View * Model * RotationMatrix * Object
然后,RotationMatrix
适用于对象。
如果我了解您的需求,那么您想要:
World = View * WorldRotationMatrix * Model * Object
然后,您只需要求解矩阵方程,这样Model * RotationMatrix2 = WorldRotationMatrix * Model
。
因此,如果A * B = T
,A-1*A * B = A-1*T => B = A-1 * T
RotationMatrix2 = Model-1 * WorldRotationMatrix * Model
在上面的注释中,-1
表示矩阵的求逆。
请看看here