101 lines
2.3 KiB
C
101 lines
2.3 KiB
C
const vec3 WORLD_UP = {0.0f, 0.0f, 1.0f};
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typedef struct camera {
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vec3 position;
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vec3 front;
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vec3 right;
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float yaw;
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float pitch;
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mat4 view_mat;
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} camera_t;
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void
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camera_update_view(camera_t* camera)
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{
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// Create orthonormal basis for camera orientation
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vec3 target = vec3_add(camera->position, camera->front);
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vec3 front = vec3_normalize(vec3_sub(target, camera->position));
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vec3 side = vec3_normalize(vec3_cross(front, WORLD_UP));
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vec3 up = vec3_cross(side, front);
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// Create an inverse rotation matrix
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// Orthogonal inverse is a simple transpose where the columns become the rows
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// +X: Right
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// +Y: Forward
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// +Z: Up
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mat4 view_mat = {
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side.x, side.y, side.z, -vec3_dot(camera->position, side),
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up.x, up.y, up.z, -vec3_dot(camera->position, up),
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front.x, front.y, front.z, -vec3_dot(camera->position, front),
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0.0f, 0.0f, 0.0f, 1.0f
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};
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camera->view_mat = view_mat;
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}
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camera_t
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camera_create(vec3 position)
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{
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camera_t result = {
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.position = position,
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.front = {0.0f, 1.0f, 0.0f},
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.right = {1.0f, 0.0f, 0.0f},
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.yaw = 90.0f};
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camera_update_view(&result);
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return result;
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}
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void
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camera_move(camera_t* camera, vec3 velocity)
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{
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// Preserve Z
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float position_z = camera->position.z;
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// Forward/Backward
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camera->position = vec3_add(camera->position, vec3_mult(camera->front, velocity.y));
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// Left/Right
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camera->right = vec3_cross(camera->front, WORLD_UP);
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camera->position = vec3_add(camera->position, vec3_mult(vec3_normalize(camera->right), velocity.x));
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// Restore Z
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camera->position.z = position_z;
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}
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void
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camera_rotate(camera_t* camera, float offset_x, float offset_y)
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{
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camera->yaw += offset_x;
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camera->pitch += offset_y;
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// Limit the camera's up/down motion
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if (camera->pitch > 60.0f)
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{
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camera->pitch = 60.0f;
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}
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else if (camera->pitch < -60.0f)
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{
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camera->pitch = -60.0f;
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}
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// Ensure camera yaw circles around 360 degrees rather than increases indefinitely
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if (camera->yaw > 360.0f)
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{
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camera->yaw -= 360.0f;
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}
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else if (camera->yaw < -360.0f)
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{
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camera->yaw += 360.0f;
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}
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float yaw_rad = DEG_TO_RAD(camera->yaw);
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float pitch_rad = DEG_TO_RAD(camera->pitch);
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camera->front.x = cosf(yaw_rad) * cosf(pitch_rad);
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camera->front.y = sinf(yaw_rad) * cosf(pitch_rad);
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camera->front.z = sinf(pitch_rad);
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camera->front = vec3_normalize(camera->front);
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}
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