rotate with touch
Post: #1
hi,
i try to rotate a sprite with touch, works well, but when the rotation-angle is grater than 360° the rotation place in the opposite direction, here is my code:
i try to rotate a sprite with touch, works well, but when the rotation-angle is grater than 360° the rotation place in the opposite direction, here is my code:
Code:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint touchPoint = [touch locationInView:self];
_touchPoint1 = touchPoint;
_p1 = makeVector((self.bounds.size.width) - self.bounds.size.width*0.5, touchPoint.y-(self.bounds.size.height*0.5) , 0.0);
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint touchPoint = [touch locationInView:self];
_touchPoint2 = touchPoint;
_p2 = makeVector( touchPoint.x - (self.bounds.size.width*0.5) , touchPoint.y - (self.bounds.size.height*0.5) , 0.0);
_p1 = normalizeVector(_p1);
_p2 = normalizeVector(_p2);
_angle = angleBetweenVectors(_p1, _p2);
_angle = _angle*360/PI;
}
.
.
.
draw:
glRotatef(_angle, 0.0f, 0.0f, 1.0f);
.
.
.
Post: #2
What does your angleBetweenVectors() function look like? I'm guessing the problem is in there.
Scott Lembcke - Howling Moon Software
Author of Chipmunk Physics - A fast and simple rigid body physics library in C.
Post: #3Skorche Wrote:What does your angleBetweenVectors() function look like? I'm guessing the problem is in there.
sorry, I forgot it:
Code:
double angleBetweenVectors(const Vector v1, const Vector v2)
{
float dot = dotProduct(v1, v2);
return asin( dot);
}
Post: #5Frank C. Wrote:http://www.idevgames.com/forum/showthread.php?t=17440
http://www.paradeofrain.com/2009/07/inte...rotations/
thanks for suggestions, i moved to quaternions, but the behavior is the same, here what i have:
Code:
float matrix[16];
_rotationY = createQuaternionFromAxisAngle(0, 0, 1, _angle);
convertQuaternionToMatrix(_rotationY, matrix);
glMultMatrixf(matrix);
.
.
.
render
createQuaternionFromAxisAngle(const float x, const float y, const float z, const float degree)
{
Quaternion v;
float angle = (float)((degree / 180.0f) * PI);
float result = (float)sin( angle / 2.0f );
v.w = (float)cos( angle / 2.0f );
v.x = (float)(x * result);
v.y = (float)(y * result);
v.z = (float)(z * result);
return v;
}
convertQuaternionToMatrix(Quaternion q, float *matrix)
{
if(!matrix) return;
// First row
matrix[ 0] = 1.0f - 2.0f * ( q.y * q.y + q.z * q.z );
matrix[ 1] = 2.0f * (q.x * q.y + q.z * q.w);
matrix[ 2] = 2.0f * (q.x * q.z - q.y * q.w);
matrix[ 3] = 0.0f;
// Second row
matrix[ 4] = 2.0f * ( q.x * q.y - q.z * q.w );
matrix[ 5] = 1.0f - 2.0f * ( q.x * q.x + q.z * q.z );
matrix[ 6] = 2.0f * (q.z * q.y + q.x * q.w );
matrix[ 7] = 0.0f;
// Third row
matrix[ 8] = 2.0f * ( q.x * q.z + q.y * q.w );
matrix[ 9] = 2.0f * ( q.y * q.z - q.x * q.w );
matrix[10] = 1.0f - 2.0f * ( q.x * q.x + q.y * q.y );
matrix[11] = 0.0f;
// Fourth row
matrix[12] = 0;
matrix[13] = 0;
matrix[14] = 0;
matrix[15] = 1.0f;
}
Post: #6
i have got it :-). The problem is not to use quaternions (in my case). I change the angle-calculation to:
thanks for the tipps
Code:
_angle = angleBetweenVectors(_p1, _p2);
_angle = _angle*180/PI;
double angleBetweenVectors(const CFXVector v1, const CFXVector v2)
{
return (atan2(v1.x*v2.y - v2.x*v1.y , v1.x*v2.x+v1.y*v2.y) );
}thanks for the tipps
Post: #7
The cool and useful thing about Quaternions or Spinors is that you don't have to screw around with angles and matrixes (at least not until render time). Converting an angle into a quaternion, then converting that to a matrix is completely pointless 
Glad you got it working regardless.
Glad you got it working regardless.
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