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# moldyviolinist

Member Since 21 Mar 2013
Offline Last Active Aug 15 2014 08:52 AM

### In Topic: [C++] First person mouse look camera controller for variable gravity, orienta...

24 April 2014 - 03:46 PM

Solved it. See http://gamedev.stackexchange.com/questions/73588/how-do-i-fix-my-planet-facing-camera for a pretty good explanation. I'll post the code here.

```glm::mat4 trans;
float factor = 1.0f;
float real_vertical = vertical;
m_horizontal += horizontal;
m_vertical += vertical;

while (m_horizontal > TWO_PI) {
m_horizontal -= TWO_PI;
}

while (m_horizontal < -TWO_PI) {
m_horizontal += TWO_PI;
}

if (m_vertical > MAX_VERTICAL) {
m_vertical = MAX_VERTICAL;
}
else if (m_vertical < -MAX_VERTICAL) {
m_vertical = -MAX_VERTICAL;
}

glm::quat world_axes_rotation = glm::angleAxis(m_horizontal * ONEEIGHTY_PI, glm::vec3(0.0f, 1.0f, 0.0f));
world_axes_rotation = glm::normalize(world_axes_rotation);
world_axes_rotation = glm::rotate(world_axes_rotation, m_vertical * ONEEIGHTY_PI, glm::vec3(1.0f, 0.0f, 0.0f));

m_pole = glm::normalize(m_pole - glm::dot(m_orientation, m_pole) * m_orientation);

glm::mat4 local_transform;

local_transform[0] = glm::vec4(m_pole.x, m_pole.y, m_pole.z, 0.0f);
local_transform[1] = glm::vec4(m_orientation.x, m_orientation.y, m_orientation.z, 0.0f);
glm::vec3 tmp = glm::cross(m_pole, m_orientation);
local_transform[2] = glm::vec4(tmp.x, tmp.y, tmp.z, 0.0f);
local_transform[3] = glm::vec4(m_position.x, m_position.y, m_position.z, 1.0f);

world_axes_rotation = glm::normalize(world_axes_rotation);
m_view = local_transform * glm::mat4_cast(world_axes_rotation);
m_direction = -1.0f * glm::vec3(m_view[2]);
m_up = glm::vec3(m_view[1]);
m_right = glm::vec3(m_view[0]);

m_view = glm::inverse(m_view);
```

### In Topic: Collision detection and walking around environment

18 April 2014 - 10:30 AM

I think ray-casting is probably the best way to do collision detection with terrain or ground meshes. Bullet has a built-in ray testing function (a member of the btCollisionWorld) that should be quite optimized.

### In Topic: [C++] First person mouse look camera controller for variable gravity, orienta...

18 April 2014 - 10:25 AM

I'm going to bump this with my most recent attemps. I still haven't solved this issue.

I'll post all the code I've tried. There are comments above each block that indicate the issue with that particular implementation. Surely someone has implemented this type of camera at some point? I would be happy to basically copy someone else's implementation for this rather than attempt to fix my own work, if necessary.

```void Camera::set_angles_advanced(float horizontal, float vertical) {

glm::mat4 trans;
float factor = 1.0f;
float real_vertical = vertical;
m_horizontal += horizontal;
m_vertical += vertical;

while (m_horizontal > TWO_PI) {
m_horizontal -= TWO_PI;
}

while (m_horizontal < -TWO_PI) {
m_horizontal += TWO_PI;
}

if (m_vertical > MAX_VERTICAL) {
vertical -= m_vertical - MAX_VERTICAL;

if (vertical < 0) {
vertical = 0;
}

m_vertical = MAX_VERTICAL;
}
else if (m_vertical < -MAX_VERTICAL) {
vertical -= m_vertical - MAX_VERTICAL;

if (vertical > 0) {
vertical = 0;
}

m_vertical = -MAX_VERTICAL;
}

// -------------------- south pole rotation
/*glm::quat rotation;

if (m_orientation != glm::vec3(0.0f, 1.0f, 0.0f)) {
glm::vec3 axis = glm::normalize(glm::cross(glm::vec3(0.0f, 1.0f, 0.0f), m_orientation));
rotation = glm::rotate(rotation, acosf(m_orientation.y) * ONEEIGHTY_PI, axis);
}

rotation = glm::rotate(rotation, m_horizontal * ONEEIGHTY_PI, glm::vec3(0.0f, 1.0f, 0.0f));
rotation = glm::rotate(rotation, m_vertical * ONEEIGHTY_PI, glm::vec3(1.0f, 0.0f, 0.0f));

m_direction = glm::vec3(rotation * glm::vec4(0.0f, 0.0f, -1.0f, 0.0f));*/

// --------------------- south pole rotation
/*glm::vec3 tmp = m_orientation;
float look_factor = 1.0f;

if (tmp.y < 0.0f) {
tmp.y *= -1.0f;
look_factor = -1.0f;
}

glm::mat4 yaw = glm::rotate(glm::mat4(), m_horizontal * ONEEIGHTY_PI, m_orientation);
glm::mat4 pitch = glm::rotate(glm::mat4(), m_vertical * -ONEEIGHTY_PI, glm::vec3(1.0f, 0.0f, 0.0f));

if (tmp != glm::vec3(0.0f, 1.0f, 0.0f)) {
glm::vec3 axis = glm::normalize(glm::cross(glm::vec3(0.0f, 1.0f, 0.0f), tmp));
pitch = glm::rotate(glm::mat4(), acosf(tmp.y) * ONEEIGHTY_PI * look_factor + addition, axis) * pitch;
}

glm::mat4 cam = yaw * pitch;

m_direction = glm::vec3(cam[2]);*/

// -------------------- oscillation when looking close to vertical, vertical range capped
/*glm::mat4 yaw_matrix = glm::rotate(glm::mat4(), m_horizontal * ONEEIGHTY_PI, m_orientation);

m_right = glm::cross(m_direction, m_orientation);

glm::mat4 pitch_matrix = glm::rotate(glm::mat4(), m_vertical * -ONEEIGHTY_PI, glm::normalize(m_right));

glm::mat4 camera_matrix = pitch_matrix * yaw_matrix;
m_direction = glm::vec3(camera_matrix[2]);*/

// --------------------- oscillation when looking close to vertical, vertical range always capped to -90,90
/*glm::mat4 yaw = glm::rotate(glm::mat4(), m_horizontal * ONEEIGHTY_PI, m_orientation);
glm::mat4 pitch = glm::rotate(glm::mat4(), m_vertical * -ONEEIGHTY_PI, m_right);

glm::mat4 cam = pitch * yaw;

m_right = glm::vec3(cam[0]);
m_up = glm::vec3(cam[1]);
m_direction = glm::vec3(cam[2]);*/

// ----------------------- south pole rotation
/*glm::dvec3 dir = glm::dvec3(cos(m_vertical) * sin(m_horizontal),
sin(m_vertical),
cos(m_vertical) * cos(m_horizontal));

glm::vec3 tmp = m_orientation;
tmp.y = fabs(tmp.y);

glm::dmat4 dtrans;
float angle;

if (glm_sq_distance(tmp, glm::vec3(0.0f, 1.0f, 0.0f)) > 0.001f) {
glm::vec3 axis = glm::normalize(glm::cross(glm::vec3(0.0f, 1.0, 0.0f), m_orientation));
angle = acos(m_orientation.y) * ONEEIGHTY_PI;
dtrans = glm::rotate(glm::mat4(), angle, axis);
}
else if (m_orientation.y < 0.0f) {
factor = -1.0f;
}

dir = glm::dvec3(dtrans * glm::dvec4(dir.x, dir.y, dir.z, 0.0f));
m_direction = glm::vec3(dir);*/

m_dir_horizontal_norm = glm::normalize(m_direction - glm_project(m_direction, m_orientation));

m_view = glm::lookAt(m_position, m_position + m_direction, m_orientation);
m_vp = m_perspective * m_view;
}
```

### In Topic: [C++] First person mouse look camera controller for variable gravity, orienta...

14 April 2014 - 07:42 PM

Well I tried this out. And it did fix the original problem I had, so it was clearly the weird transformation I was using. However, there are two other problems. The first is that the look direction is not automatically adjusted as the orientation changes. So the direction stays fixed in place as you move over the planets surface, which is definitely awkward. The direction needs to stay the same relative to the ground as the orientation changes. The second problem is that attempting to cap the vertical angle at which you can look seems to cap to the same section despite the orientation. Well, it's weird, if you move along and don't move the mouse much, then the look direction is capped between -90 and 90 of the original orientation (0, 1, 0), which is obviously a problem. However, putting the vertical angle at max and moving horizontally a lot seems to fix the issue, and then the cap is reset to the current orientation. Very peculiar. I can't quite imagine why that would be happening...

Here's the code I used, maybe someone can spot the issues causing the two problems I mentioned.

```void Camera::set_angles_advanced(float horizontal, float vertical) {
glm::mat4 trans;
float factor = 1.0f;
m_horizontal += horizontal;
m_vertical += vertical;

while (m_horizontal > TWO_PI) {
m_horizontal -= TWO_PI;
}

while (m_horizontal < -TWO_PI) {
m_horizontal += TWO_PI;
}

if (m_vertical > MAX_VERTICAL) {
vertical -= m_vertical - MAX_VERTICAL;

if (vertical < 0) {
vertical = 0;
}

m_vertical = MAX_VERTICAL;
}
else if (m_vertical < -MAX_VERTICAL) {
vertical -= m_vertical - MAX_VERTICAL;

if (vertical > 0) {
vertical = 0;
}

m_vertical = -MAX_VERTICAL;
}

glm::mat4 pitch = glm::rotate(glm::mat4(), vertical * ONEEIGHTY_PI, glm::normalize(m_right));
glm::mat4 yaw = glm::rotate(glm::mat4(), horizontal * ONEEIGHTY_PI, m_orientation);

m_camera = pitch * yaw * m_camera;

m_direction = glm::vec3(m_camera[2]);

m_view = glm::lookAt(m_position, m_position + m_direction, m_orientation);
m_vp = m_perspective * m_view;

m_dir_norm = glm::normalize(m_direction);
m_dir_horizontal_norm = glm::normalize(m_direction - glm_project(m_direction, m_orientation));

m_right = glm::cross(m_direction, m_orientation);
m_right_horizontal_norm = glm::normalize(m_right);
}
```

### In Topic: [C++] First person mouse look camera controller for variable gravity, orienta...

14 April 2014 - 08:06 AM

Thanks for the suggestions. I did attempt a matrix-only implementation at one point, but was unsuccessful. It's entirely possible that I had some mistakes in there, and your solution is pretty clean, so I will give that a try. I'll report back after work.

One question I have is: how OK is it to use the previous frame's right vector? I'm sure it works, but I would prefer an up-to-date right vector, is there a good way to calculate that? I ended up completely avoiding a right vector in my code. And in your pitch and yaw angle method, you're using a right vector of vec3(1,0,0), which surely isn't correct for different orientations.

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