I generated a virtual terrain consisting of quads in my code I am now trying to find the height of the terrain at a certain point. To clarify: I have a terrain with a width and depth in X and Y directions, and a height in the Z direction. I want to know at what Z a line at a specific X and Y intersects my plane.
The terrain itself is stored as quads in a two-dimensional array (the indices are the coords, I just store the height) and I'm using the following code:
(it uses the cross product of the vectors from the bottom left to bottom right and top left points)
function getTerrainHeight(float x, float y) {
int ix = (int)x;
int iy = (int)y;
Vector3 V1 = new Vector3(ix,iy,heights[ix][iy]);
Vector3 V2 = new Vector3(ix+1, iy, heights[ix + 1][iy]);
Vector3 V3 = new Vector3(ix, iy+1, heights[ix][iy+1]);
if ((x-ix) + (y-iy) > 1)
{
V1 = new Vector3(ix + 1, iy + 1, heights[ix + 1][iy + 1]);
}
Vector3 cross = Vector3.Cross(V2-V1,V3-V1);
return (cross.X * (x - ix) + cross.Y * (y - iy)) / -cross.Z + heights[ix][iy];
}
This kinda works, but there are some mismatches, when I go over the terrain there are alway some dents where the height is lower than it should be. Does anybody know what's going wrong?
Related
I'm setting up an automatic system to be able to attach a sprite and it will gather all its colours and the world position of each sprite. A list/class of all the colours used has been set up but how would get the position of all these sprites?
I have already tried doing this mathematically like getting the complete size of the sprite and then working out the size of each pixel and then working out the position from that. But this seems flawed due to the position of the sprite possibly changing.
Sprite ColouredSpriteTexture = ColoredSprite.GetComponent<SpriteRenderer>().sprite;
Texture2D ColouredTexture = ColouredSpriteTexture.texture;
float XsizeF = ColoredSprite.transform.localScale.x;
int Xsize = (int)XsizeF;
float YsizeF = ColoredSprite.transform.localScale.y;
int Ysize = (int)YsizeF;
List<Color> TempList = new List<Color>();
//Could spawn pixels by getting x and y size and dividing them by 100 50/100 = 0.50f
//if the tile has a color then spawn pixel if not 0.50 += 0.50
//TODO test if this logic will work
float PixelSize = XsizeF / 100;
float currentPos = PixelSize;
for (int x = 0; x < Xsize; x++)
{
for (int y = 0; y < Ysize; y++)
{
int listAmount = TempList.Count;
Color ColoredTex = ColouredTexture.GetPixel(x, y);
float TextureAlpha = ColoredTex.a;
if (!TempList.Contains(ColoredTex) && TextureAlpha != 0)
{
TempList.Add(ColoredTex);
ColorByNumber tempColor = new ColorByNumber();
tempColor.Color = ColoredTex;
tempColor.ColorNumber = listAmount;
ColorOptions.Add(tempColor);
}
if(TextureAlpha == 1)
{
GameObject ColorPixel = Instantiate(PixelPrefab);
ColorPixel.transform.localScale = new Vector3(XsizeF, YsizeF, 0);
ColorPixel.transform.SetParent(this.transform);
ColorPixel.name = "Pixel (" + x.ToString() + "," + y.ToString() + ")";
}
}
}
All I would need is somehow each pixel returning its position so I can store this data and be able to spawn anything on top of this pixel.
I haven't had a chance to test this math yet so there may be some mistakes in it:
Every graphical image in Unity has a PPU, this and the object scale are going to be a huge factor. For argument sake I am going to clearly define these for 1 object.
Image dimensions : 128x128
PPU: 64
Scale: 1,1,1
Object Bounds: would
come from the renderer, which I am unsure if that bounds already
takes in account the scale(Most likely) however in the case you
cannot use that you can calculate the ObjectBoundsWidth or height
just by dividing the width or height of the texture by the PPU.
This should give you bounds of the texture in world space.
We are also going to make an assumption that we are only working on the X and Y axis and ignore the Z axis, if you want to use Z instead of Y then just make the necessary changes to be Z Scale and Z position and Z Bounds.
World position of a pixel located at 2,10. Per the documentation the pixel coordinates start at the lower left this means 0,0 is the bottom left corner, and 2,10 is 2 pixels left and 10 pixels up.
EDIT:
So I plugged all of this into a google sheet and determined the previous algorithm I provided was wrong here is the correct one in a pseudo code format
// This function takes in either the x or y, and the width or height of
// the bounds, then the x or y position of the object attached to.
// It also assumes the pivot is the center of the sprite.
float CalculateWorldPosOfPixelCoordinate(int coord, float boundsSize, float position, float scale)
{
float PixelInWorldSpace = 1.0f / PPU;
float startPos= position - (boundsSize* 0.5f * scale);
return startPos + (PixelInWorldSpace * coord) * scale;
}
This is using objectBounds we determined ourselves that is why we are multiply by scale.
this would give use a world position of: -0.97, -0.84
The algorithm i believe is the same for Y, just replace the coord with the Y position, and the bounds with the height instead of the width.
Like I said this could be wrong as I havent had a chance to test it, this also does not account for rotation either.
Given an Point array and an arbitrary x,y coordinate, find the index for _points that is closest to the given coordinate.
PointD[] _points
//create a list of x,y coordinates:
for (int i = 0; i < _numberOfArcSegments + 1; i++)
{
double x1 = _orbitEllipseSemiMaj * Math.Sin(angle) - _focalDistance; //we add the focal distance so the focal point is "center"
double y1 = _orbitEllipseSemiMinor * Math.Cos(angle);
//rotates the points to allow for the LongditudeOfPeriapsis.
double x2 = (x1 * Math.Cos(_orbitAngleRadians)) - (y1 * Math.Sin(_orbitAngleRadians));
double y2 = (x1 * Math.Sin(_orbitAngleRadians)) + (y1 * Math.Cos(_orbitAngleRadians));
angle += _segmentArcSweepRadians;
_points[i] = new PointD() { x = x2, y = y2 };
}
I'm drawing an ellipse which represents an orbit. I'm first creating the point array above, then when I draw it, I (attempt) to find the point closest to where the orbiting body is.
To do this I've been attempting to calculate the angle from the center of the ellipse to the body:
public void Update()
{
//adjust so moons get the right positions (body position - focal point position)
Vector4 pos = _bodyPositionDB.AbsolutePosition - _positionDB.AbsolutePosition;
//adjust for focal point
pos.X += _focalDistance;
//rotate to the LonditudeOfPeriapsis.
double x2 = (pos.X * Math.Cos(-_orbitAngleRadians)) - (pos.Y * Math.Sin(-_orbitAngleRadians));
double y2 = (pos.X * Math.Sin(-_orbitAngleRadians)) + (pos.Y * Math.Cos(-_orbitAngleRadians));
_ellipseStartArcAngleRadians = (float)(Math.Atan2(y2, x2)); //Atan2 returns a value between -180 and 180;
}
then:
double unAdjustedIndex = (_ellipseStartArcAngleRadians / _segmentArcSweepRadians);
while (unAdjustedIndex < 0)
{
unAdjustedIndex += (2 * Math.PI);
}
int index = (int)unAdjustedIndex;
The ellipse draws fine, (the point array is correct and all is good once adjusted for viewscreen and camera offsets and zoom)
But does not start at the correct point (I'm decreasing the alpha in the color so the resulting ellipse fades away the further it gets from the body)
I've spend days trying to figure out what I'm doing wrong here and tried a dozen different things trying to figure out where my math is wrong, but I'm not seeing it.
I assume that _points should be an array of PointD;
This is the shortest way to get the closest point to your array (calcdistance should be a simple function that calculate the euclidean distance):
PointD p = _points.OrderBy(p => CalcDistance(p, gievnPoint)).First();
Alright, so today I decided to try to further optimize my collision detection code for my tile engine.
This is what I did:
Circle class checks if there are points within range. If there are, then check for collision between player and tile.
Code:
int tileWidth = 128;
int tileHeight = 128;
int[,] Layer3 = { 1, 1, 1, etc... };
int tileMapWidth = Layer3.GetLength(1);
int tileMapHeight = Layer3.GetLength(0);
Rectangle tile, tile2;
for (int x = 0; x < tileMapWidth; x++)
{
for (int y = 0; y < tileMapHeight; y++)
{
int wallIndex = Layer3[y, x];
if (wallIndex == 1) //Full-sized Tile Collision (128 x 128)
{
if (collisionCircle.Contains(new Vector2(x * tileWidth + (tileWidth / 2) + (int)Player.camera.Position.X,
y * tileHeight + (tileHeight / 2) + (int)Player.camera.Position.Y))) //+ tile / 2 is for centering the point
{
tile = new Rectangle(x * tileWidth + (int)Player.camera.Position.X, y * tileHeight + (int)Player.camera.Position.Y, tileWidth, tileHeight);
Collide(tile);
}
}
}
}
This would check throughout layer3 if there is a "1". If there is, assign rectangle and check for collision if point is inside collision radius.
Also, I checked this code(with a draw method), and I know it's working properly, at least the behavior.
I added in about 120,000(32 x 3888) tiles to try to make it lag, and before the code, it lagged a little bit. But after I added in the code, it lagged even more so.
I thought that since it would only check for collision between tiles(points) that are within the radius it wouldn't even remotely lag, but that's not the case...
Any help/ideas on how to optimize this would be great.
Thanks a lot,
Shyy
EDIT:
Cirlce.Contains() code:
public bool Contains(Vector2 Point)
{
return ((Point - position).Length() <= radius);
}
I used a circle because I've heard it's faster than using a rectangle.
Another possible optimization is instead of
return ((Point - position).Length() <= radius);
use
return ((Point - position).LengthSquared() <= radius * radius);
This is faster because Vector2.Length() has to perform a costly square root operation. Vector2.LengthSquared() does not have to perform that slow operation. The radius has to be multiplied by itself to account for the length from the vector being squared.
It sounds like you're trying to determine what tiles you don't need to use for collision with the player. Another optimization you could do is that if a tile at (X=5,Y=5) is above and to the left of the player, then you don't need to check a tile at (X=4,Y=4). Similarly if (X=5,Y=5) is below and to the right, (X=6,Y=6) is guaranteed to be too far as well. Try to determine when you've passed the player and no longer need to check collisions.
I suggest to loop only over visible tiles in screen to check collision using movement offset.
i will try something from my head..
for x as integer = 0 + offSetX to tilesInWidth + offSetX
for y as integer = 0 + offSetY to tilesInHeight + offSetY
if player.insideCircle(player.position, radius) '
object = layer(y,x);
if player.collideWith(object) then Collide()
end if
next
next
I wanted to know if writing points using a for loop in the begin end batch works or not, so I read up on a sphere algorithm and produced this based on my reading. There are some problems with it as you can see below in the output screen capture. My goal is to produce a sphere procedurally and then modify it at runtime.
but I would like to set my goal on the short-term and figure out why the faces are not correct. anyone have any ideas?
I've got this code:
private void openGLControl_OpenGLDraw(object sender, RenderEventArgs e)
{
// Get the OpenGL object.
OpenGL gl = openGLControl.OpenGL;
// Clear the color and depth buffer.
gl.Clear(OpenGL.GL_COLOR_BUFFER_BIT | OpenGL.GL_DEPTH_BUFFER_BIT);
// Load the identity matrix.
gl.LoadIdentity();
// Rotate around the Y axis.
gl.Rotate(rotation, 0.0f, 1.0f, 0.0f);
//Draw a ball
//Drawing Mode
gl.PolygonMode(SharpGL.Enumerations.FaceMode.FrontAndBack, SharpGL.Enumerations.PolygonMode.Lines);
//ball fields
double radius = 4.0d;
const double DEGREE = Math.PI/11.25;
double x = 0;
double y = 0;
double z = 0;
// ball batch
gl.Begin(OpenGL.GL_TRIANGLE_STRIP_ADJACENCY);
for (double j = 0.0d; j < Math.PI; j = j +DEGREE)
{
for (double i = 0; i < 2 * Math.PI; i = i + DEGREE)
{
x = radius * Math.Cos(i) * Math.Sin(j);
y = radius * Math.Sin(j) * Math.Sin(i);
z = radius * Math.Cos(j);
gl.Color(Math.Abs(x + y), Math.Abs(y + z), Math.Abs(z + x));
gl.Vertex(x, y, z);
}
}
gl.End();
// Nudge the rotation.
rotation += 3.0f;
}
I am using the following to create a circle using VertexPositionTexture:
public static ObjectData Circle(Vector2 origin, float radius, int slices)
{
/// See below
}
The texture that is applied to it doesn't look right, it spirals out from the center. I have tried some other things but nothing does it how I want. I would like for it to kind-of just fan around the circle, or start in the top-left end finish in the bottom-right. Basically wanting it to be easier to create textures for it.
I know that are MUCH easier ways to do this without using meshes, but that is not what I am trying to accomplish right now.
This is the code that ended up working thanks to Pinckerman:
public static ObjectData Circle(Vector2 origin, float radius, int slices)
{
VertexPositionTexture[] vertices = new VertexPositionTexture[slices + 2];
int[] indices = new int[slices * 3];
float x = origin.X;
float y = origin.Y;
float deltaRad = MathHelper.ToRadians(360) / slices;
float delta = 0;
float thetaInc = (((float)Math.PI * 2) / vertices.Length);
vertices[0] = new VertexPositionTexture(new Vector3(x, y, 0), new Vector2(.5f, .5f));
float sliceSize = 1f / slices;
for (int i = 1; i < slices + 2; i++)
{
float newX = (float)Math.Cos(delta) * radius + x;
float newY = (float)Math.Sin(delta) * radius + y;
float textX = 0.5f + ((radius * (float)Math.Cos(delta)) / (radius * 2));
float textY = 0.5f + ((radius * (float)Math.Sin(delta)) /(radius * 2));
vertices[i] = new VertexPositionTexture(new Vector3(newX, newY, 0), new Vector2(textX, textY));
delta += deltaRad;
}
indices[0] = 0;
indices[1] = 1;
for (int i = 0; i < slices; i++)
{
indices[3 * i] = 0;
indices[(3 * i) + 1] = i + 1;
indices[(3 * i) + 2] = i + 2;
}
ObjectData thisData = new ObjectData()
{
Vertices = vertices,
Indices = indices
};
return thisData;
}
public static ObjectData Ellipse()
{
ObjectData thisData = new ObjectData()
{
};
return thisData;
}
ObjectData is just a structure that contains an array of vertices & an array of indices.
Hope this helps others that may be trying to accomplish something similar.
It looks like a spiral because you've set the upper-left point for the texture Vector2(0,0) in the center of your "circle" and it's wrong. You need to set it on the top-left vertex of the top-left slice of you circle, because 0,0 of your UV map is the upper left corner of your texture.
I think you need to set (0.5, 0) for the upper vertex, (1, 0.5) for the right, (0.5, 1) for the lower and (0, 0.5) for the left, or something like this, and for the others use some trigonometry.
The center of your circle has to be Vector2(0.5, 0.5).
Regarding the trigonometry, I think you should do something like this.
The center of your circle has UV value of Vector2(0.5, 0.5), and for the others (supposing the second point of the sequence is just right to the center, having UV value of Vector2(1, 0.5)) try something like this:
vertices[i] = new VertexPositionTexture(new Vector3(newX, newY, 0), new Vector2(0.5f + radius * (float)Math.Cos(delta), 0.5f - radius * (float)Math.Sin(delta)));
I've just edited your third line in the for-loop. This should give you the UV coordinates you need for each point. I hope so.