I set up my ortho projection like this :
transform = glm::ortho(0.0f, width, height, 0.0f);
this works pretty well, but when I want to use the glm::rotate function like this:
transform = glm::rotate(transform, glm::radians(45.0f), glm::vec3(0, 0, 1));
my object rotates around 0 : 0 : 0.
my vertices look like this:
GLfloat vertices[] = {
600, 100, 0,
612, 100, 0,
612, 130, 0,
600, 130, 0
};
how can I make my object rotate around its center ?
CodePudding user response：
If you want to rotate around its center you have to:
- Translate the object so that the center of the object is moved to (0, 0).
- Rotate the object.
- Move the object so that the center point moves in its original position.
GLfloat center_x = 606.0f;
GLfloat center_y = 115.0f;
transform = glm::translate(transform, glm::vec3(center_x, center_y, 0));
transform = glm::rotate(transform, glm::radians(45.0f), glm::vec3(0, 0, 1));
transform = glm::translate(transform, glm::vec3(-center_x, -center_y, 0));