How to make 3d camera infinitely rotate around with SDL2 mouse motion? - c++

Question

I am trying to implement 3D camera mouse rotation. Right now what I can do is only rotate if my mouse is in the bound of the window. What it means is if my window is 1280 width I cannot rotate more if mouse coordinates rich 0 or 1279. I've read that relative mouse should help. It does not work for me though.
before the main loop
SDL_ShowCursor(SDL_DISABLE);
SDL_SetRelativeMouseMode(SDL_TRUE);
SDL_WarpMouseInWindow(window, SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2);
The function that rotates xyz
glm::vec3 MouseMotion(float x, float y)
{
float lastX = SCREEN_WIDTH / 2, lastY = SCREEN_HEIGHT / 2;
float pitch = 0.0f, yaw = -90.0f;
float offsetX = x - lastX;
float offsetY = lastY - y;
lastX = x;
lastY = y;
float sensitivity = 0.3f;
yaw += offsetX * sensitivity;
pitch += offsetY * sensitivity;
if (pitch > 89.0f)
pitch = 89.0f;
if (pitch < -89.0f)
pitch = -89.0f;
glm::vec3 front;
front.x = std::cos(glm::radians(yaw)) * std::cos(glm::radians(pitch));
front.y = std::sin(glm::radians(pitch));
front.z = std::sin(glm::radians(yaw)) * std::cos(glm::radians(pitch));
//std::cout << "Mouse: " << offsetX << ", " << offsetY << std::endl;
//std::cout << "YAW AND PITCH: " << yaw << ", " << pitch << std::endl;
return glm::normalize(front);
}
and the event loop
while (SDL_PollEvent(&event))
{
if (event.type == SDL_QUIT)
{
exit(0);
}
if (event.type == SDL_MOUSEMOTION)
{
float mouseX = (float)event.motion.x;
float mouseY = (float)event.motion.y;
cameraFront = MouseMotion(mouseX, mouseY);
}
}
it is working, but only if my mouse is in the bound.
Changing to event.motion.xrel and event.motion.yrel do not fix this. It makes it more bugged because my camera shakes, i.e. going a little bit right and get back to center or left and back to center.
How to make my camera move fully, infinitely move around?

Answer 1

Following on from the comments, here is a list of problems:
You need to call SDL_WarpMouseInWindow every time after an SDL_MOUSEMOTION event to reset the mouse, or it will quickly hit the "bound" you were talking about.
pitch and yaw need to be higher in scope than the game loop, or they will be reset every time and you won't be able to achieve "infinite rotation".
sensitivity is far too high. A typical mouse movement of ~500 units translates to a ~180 degree turning.
Here is an attempt at fixing the above issues, with some code refactoring:
glm::vec3 polarVector(float p, float y)
{
// this form is already normalized
return glm::vec3(std::cos(y) * std::cos(p),
std::sin(p),
std::sin(y) * std::cos(p));
}
// clamp pitch to [-89, 89]
float clampPitch(float p)
{
return p > 89.0f ? 89.0f : (p < -89.0f ? -89.0f : p);
}
// clamp yaw to [-180, 180] to reduce floating point inaccuracy
float clampYaw(float y)
{
float temp = (y + 180.0f) / 360.0f;
return y - ((int)temp - (temp < 0.0f ? 1 : 0)) * 360.0f;
}
int main(int argc, char*args[])
{
// ...
// experiment with this
const float sensitivity = 0.001f;
#define CTR_X (SCREEN_WIDTH / 2)
#define CTR_Y (SCREEN_HEIGHT / 2)
#define RESET_MOUSE SDL_WarpMouseInWindow(window, CTR_X, CTR_Y)
// call once at the start
RESET_MOUSE;
// keep outside the loop
float pitch = 0.0f, yaw = 0.0f;
while (!quit)
{
// ...
while (SDL_PollEvent(&event))
{
if (event.type == SDL_QUIT)
{
exit(0);
}
if (event.type == SDL_MOUSEMOTION)
{
float deltaX = (float)event.motion.x - CTR_X;
float deltaY = (float)event.motion.y - CTR_Y;
yaw = clampYaw(yaw + sensitivity * deltaX);
pitch = clampPitch(pitch - sensitivity * deltaY);
// assumes radians input
cameraFront = polarVector(glm::radians(pitch), glm::radians(yaw));
// reset *every time*
RESET_MOUSE;
}
}
// ...
}
}