SDL OpenGL smooth camera movement - opengl

Question

I am trying to implement a camera motion system into the program I am currently working on. I cant figure out how to move the camera in non-discrete units so when I move the camera it "jumps" to the next position. how can I move the camera smoothly without jumps.
CameraControlls Function:
void CameraControlls()
{
while (SDL_PollEvent(&e))
{
if (e.type == SDL_QUIT)
{
exit(0);
}
switch (e.type)
{
case SDL_KEYDOWN:
switch (e.key.keysym.sym)
{
case SDLK_w:
cam.MoveForward(0.3f);
break;
case SDLK_s:
cam.MoveBackward(0.3f);
break;
case SDLK_d:
cam.MoveRight(0.2f);
break;
case SDLK_a:
cam.MoveLeft(0.2f);
break;
case SDLK_ESCAPE:
exit(0);
break;
case SDLK_RIGHT:
cam.Yaw(-0.01f);
break;
case SDLK_LEFT:
cam.Yaw(0.01f);
break;
case SDLK_DOWN:
cam.Pitch(0.01f);
break;
case SDLK_UP:
cam.Pitch(-0.01f);
break;
}
}
}
}
Camera Structure:
struct Camera
{
public:
Camera(glm::vec3& pos, float fov, float aspect, float zNear, float zFar)
{
this->pos = pos;
this->forward = glm::vec3(0.0f, 0.0f, 1.0f);
this->up = glm::vec3(0.0f, 1.0f, 0.0f);
this->projection = glm::perspective(fov, aspect, zNear, zFar);
}
inline glm::mat4 GetViewProjection() const
{
return projection * glm::lookAt(pos, pos + forward, up);
}
void MoveBackward(float amt)
{
pos -= forward*amt;
}
void MoveForward(float amt)
{
pos += forward * amt;
}
void MoveRight(float amt)
{
pos -= glm::cross(up, forward) * amt;
}
void MoveLeft(float amt)
{
pos += glm::cross(up, forward) * amt;
}
void Pitch(float angle)
{
glm::vec3 right = glm::normalize(glm::cross(up, forward));
forward = glm::vec3(glm::normalize(glm::rotate(angle, right) * glm::vec4(forward, 0.0)));
up = glm::normalize(glm::cross(forward, right));
}
void Yaw(float angle)
{
static const glm::vec3 UP(0.0f, 1.0f, 0.0f);
glm::mat4 rotation = glm::rotate(angle, UP);
forward = glm::vec3(glm::normalize(rotation * glm::vec4(forward, 0.0)));
up = glm::vec3(glm::normalize(rotation * glm::vec4(up, 0.0)));
}
private:
glm::mat4 projection;
glm::vec3 pos;
glm::vec3 forward;
glm::vec3 up;
};

Answer 1

I guess the key event of sdl is not firing every frame so you shouldn't change the camera position directly from there because camera wont update every frame.
I would create a boolean variable MOVE_FORWARD that will represent if the forward key is pushed or not
In the key event you update the MOVE_FORWARD variable.
while (SDL_PollEvent(&e))
{
..........
case SDL_KEYDOWN:
switch (e.key.keysym.sym)
{
case SDLK_w:
MOVE_FORWARD=true;
break;
In every frame you update the position of the camera
if (MOVE_FORWARD){pos+=0.3}
This way the camera updates its position every frame and not only when the key event fires
You could also avoid creating key state variables using SDL_GetKeyboardState(NULL) instead of SDL_PollEvent(&e):
Uint8* keystate = SDL_GetKeyState(NULL);
if(keystate[SDL_SCANCODE_W])
{
pos+=0.3;
}