Calculating angle a segment forms with a ray

Posted by kr1zz on Game Development See other posts from Game Development or by kr1zz
Published on 2014-08-20T15:30:15Z Indexed on 2014/08/20 16:37 UTC
Read the original article Hit count: 423

Filed under:

geometry

|

angles

I am given a point C and a ray r starting there. I know the coordinates (xc, yc) of the point C and the angle theta the ray r forms with the horizontal, theta in (-pi, pi]. I am also given another point P of which I know the coordinates (xp, yp): how do I calculate the angle alpha that the segment CP forms with the ray r, alpha in (-pi, pi]?

Some examples follow: example 1 example 2 example 3

I can use the the atan2 function.

© Game Development or respective owner

Related posts about geometry

GLSL check if fragment is on geometry

as seen on Stack Overflow - Search for 'Stack Overflow'
I am currently writing the positions of my geometry to the RGB channels of gl_FragColor and I would like to write 1.0 to the alpha channel if the fragment is part of geometry, and 0.0 if its empty. Is there a simple way to tell if a fragment is geometry or not? Maybe through gl_FragCoord.z? thanks >>> More
In JTS, when I do geometry.buffer(1).buffer(-1), will the resulting geometry be equivalent to the or

as seen on Stack Overflow - Search for 'Stack Overflow'
I was having problems while intersecting two geometries, getting a TopologyException probably due to a rounding error during the operation, then I read this fix and tried a buffer(0) on both input geometries, but still without success. Then I tried geo.buffer(1).buffer(-1) and it worked. Will these… >>> More
Multiple mesh with one geometry and diferent textures. Error

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a loop where I create a multiple Mesh with different geometry, because each mesh has one texture: .... var geoCube = new THREE.CubeGeometry(voxelSize, voxelSize, voxelSize); var geometry = new THREE.Geometry(); for( var i = 0; i < voxels.length; i++ ){ var voxel = voxels[i]; var object; … >>> More
How to read verbose VC++ linker output

as seen on Stack Overflow - Search for 'Stack Overflow'
Trying to debug some linker errors, I turned on /VERBOSE and I'm trying to make sense of the output. It occurs to me that I really don't know how to read it. For example: 1>Compiling version info 1>Linking... 1>Starting pass 1 1>Processed /DEFAULTLIB:mfc80.lib 1>Processed /DEFAULTLIB:mfcs80… >>> More
Drawing a rectangular prism using opengl

as seen on Game Development - Search for 'Game Development'
I'm trying to learn opengl. I did some code for building a rectangular prism. I don't want to draw back faces so I used glCullFace(GL_BACK), glEnable(GL_CULL_FACE);. But I keep getting back faces also when viewing from front and also sometimes when rotating sides are vanishing. Can someone point me… >>> More

Related posts about angles

Quaternion dfference + time --> angular velocity (gyroscope in physics library)

as seen on Game Development - Search for 'Game Development'
I am using Bullet Physic library to program some function, where I have difference between orientation from gyroscope given in quaternion and orientation of my object, and time between each frame in milisecond. All I want is set the orientation from my gyroscope to orientation of my object in 3D space… >>> More
what does AngleVectors method in quake 3 source code does

as seen on Game Development - Search for 'Game Development'
I just downloaded quake 3 for learning purposes. I know some of some linear algebra(basic vector math ie: dot,cross product). However I can't decipher what below method does, I know what is yaw,pitch and roll. But I can't connect these with vector. Worse, I'm not sure this fall under what math 'category'… >>> More
Calculating angle a segment forms with a ray

as seen on Game Development - Search for 'Game Development'
I am given a point C and a ray r starting there. I know the coordinates (xc, yc) of the point C and the angle theta the ray r forms with the horizontal, theta in (-pi, pi]. I am also given another point P of which I know the coordinates (xp, yp): how do I calculate the angle alpha that the segment… >>> More
(Libgdx) Move Vector2 along angle?

as seen on Game Development - Search for 'Game Development'
I have seen several answers on here about moving along angle, but I can't seem to get this to work properly for me and I am new to LibGDX... just trying to learn. These are my Vector2's that I am using for this function. public Vector2 position = new Vector2(); public Vector2 velocity = new Vector2(); public… >>> More
Ball bouncing at a certain angle and efficiency computations

as seen on Game Development - Search for 'Game Development'
I would like to make a pong game with a small twist (for now). Every time the ball bounces off one of the paddles i want it to be under a certain angle (between a min and a max). I simply can't wrap my head around how to actually do it (i have some thoughts and such but i simply cannot implement… >>> More