In XNA 4.0 3D. I want to Drag and Drop one model 3D.So,I must check mouse in a Model or not. My problem is I don't know change position and rate this Model from 3D to 2D. It's related Matrix View and Matrix Projection of camera??
This is my code:
http://www.mediafire.com/?3835txmw3amj7pe
Check out this article on msdn: Selecting an Object with a Mouse.
From that article:
MouseState mouseState = Mouse.GetState();
int mouseX = mouseState.X;
int mouseY = mouseState.Y;
Vector3 nearsource = new Vector3((float)mouseX, (float)mouseY, 0f);
Vector3 farsource = new Vector3((float)mouseX, (float)mouseY, 1f);
Matrix world = Matrix.CreateTranslation(0, 0, 0);
Vector3 nearPoint = GraphicsDevice.Viewport.Unproject(nearsource,
proj, view, world);
Vector3 farPoint = GraphicsDevice.Viewport.Unproject(farsource,
proj, view, world);
// Create a ray from the near clip plane to the far clip plane.
Vector3 direction = farPoint - nearPoint;
direction.Normalize();
Ray pickRay = new Ray(nearPoint, direction);
For proj and view use your own projection and view matrices accordingly.
Now when you have your Ray, you need to have a BoundingBox or a BoundingSphere (or multiple) that are roughly encompassing your model.
A simple solution is to use BoundingSphere properties of ModelMesh for each mesh in your Model.Meshes.
foreach(ModelMesh mesh in model.Meshes)
{
if(Ray.Intersects(mesh.BoundingSphere))
{
//the mouse is over the model!
break;
}
}
Since BoundingSphere of each ModelMesh is going to encompass all vertices in that mesh, it might not be the most precise representation of the mesh if it is not roughly round (i.e. if it is very long). This means that the above code could be saying that the mouse intersects the object, when visually it is way off.
The alternative is to create your bounding volumes manually. You make instances of BoundingBox or BoundingSphere objects as suits your need, and manually change their dimensions and positions based on runtime requirements. This requires slightly more work, but it isn't hard.
Related
I have a Goldberg polyhedron that I have procedurally generated. I would like to draw an outline effect around a group of “faces” (let's call them tiles) similar to the image below, preferably without generating two meshes, doing the scaling in the vertex shader. Can anyone help?
My assumption is to use a scaled version of the tiles to write into a stencil buffer, then redraw those tiles comparing the stencil to draw the outline (as usual for this kind of effect), but I can't come up with an elegant solution to scale the tiles.
My best idea so far is to get the center point of the neighbouring tiles (green below) for each edge vertex (blue) and move the vertex towards them weighted by how many there are, which would leave the interior ones unmodified and the exterior ones moved inward. I think this works in principle, but I would need to generate two meshes as I couldn't do scaling this way in the vertex shader (as far as I know).
If it’s relevant this is how the polyhedron is constructed. Each tile is a separate object, the surface is triangulated with a central point and there is another point at the polyhedron’s origin (also the tile object’s origin). This is just so the tiles can be scaled uniformly and protrude from the polyhedron without creating gaps or overlaps.
Thanks in advance for any help!
EDIT:
jsb's answer was a simple and elegant solution to this problem. I just wanted to add some extra information in case someone else has the same problem.
First, here is the C# code I used to calculate these UVs:
// Use duplicate vertex count (over 4)
var vertices = mesh.vertices;
var uvs = new Vector2[vertices.Length];
for(int i = 0; i < vertices.Length; i++)
{
var duplicateCount = vertices.Count(s => s == vertices[i]);
var isInterior = duplicateCount > 4;
uvs[i] = isInterior ? Vector2.zero : Vector2.one;
}
Note that this works because I have not welded any vertices in my original mesh so I can count the adjoining triangles by just looking for duplicate vertices.
You can also do it by counting triangles like this (this would work with merged vertices, at least with how Unity's mesh data is laid out):
// Use triangle count using this vertex (over 4)
var triangles = mesh.triangles;
var uvs = new Vector2[mesh.vertices.Length];
for(int i = 0; i < triangles.Length; i++)
{
var triCount = triangles.Count(s => mesh.vertices[s] == mesh.vertices[triangles[i]]);
var isInterior = triCount > 4;
uvs[i] = isInterior ? Vector2.zero : Vector2.one;
}
Now on to the following problem. In my use case I also need to generate outlines for irregular tile patterns like this:
I neglected to mention this in the original post. Jsb's answer is still valid but the above code will not work as is for this. As you can see, when we have a tile that is only connected by one edge, the connecting vertices only "share" 2 interior triangles so we get an "exterior" edge. As a solution to this I created extra vertices along the the exterior edges of the tiles like so:
I did this by calculating the half way point along the vector between the original exterior tile vertices (a + (b - a) * 0.5) and inserting a point there. But, as you can see, the simple "duplicate vertices > 4" no longer works for determining which tiles are on the exterior.
My solution was to wind the vertices in a specific order so I know that every 3rd vertex is one I inserted along the edge like this:
Vector3 a = vertex;
Vector3 b = nextVertex;
Vector3 c = (vertex + (nextVertex - vertex) * 0.5f);
Vector3 d = tileCenter;
CreateTriangle(c, d, a);
CreateTriangle(c, b, d);
Then modify the UV code to test duplicates > 2 for these vertices (every third vertex starting at 0):
// Use duplicate vertex count
var vertices = mesh.vertices;
var uvs = new Vector2[vertices.Length];
for(int i = 0; i < vertices.Length; i++)
{
var duplicateCount = vertices.Count(s => s == vertices[i]);
var isMidPoint = i % 3 == 0;
var isInterior = duplicateCount > (isMidPoint ? 2 : 4);
uvs[i] = isInterior ? Vector2.zero : Vector2.one;
}
And here is the final result:
Thanks jsb!
One option that avoids a second mesh would be texturing:
Let's say you define 1D texture coordinates on the triangle vertices like this:
When rendering the mesh, use these coordinates to look up in a 1D texture which defines the interior and border color:
Of course, instead of using a texture, you can just as well implement this behavior in a fragment shader by thresholding the texture coordinate, conceptually:
if (u > 0.9)
fragColor = white;
else
fragColor = gray;
To update the outline, you would only need upload a new set of tex coords, which are just 1 for vertices on the outline and 0 everywhere else.
Depending on whether you want the outlines to extend only into the interior of the selected region or symmetrically to both sides of the boundary, you would need to specify the tex coords either per-corner or per-vertex, respectively.
So I'm trying to "outline" 3D objects. Standard problem, for which the answer is meant to be that you copy the mesh, color it the outline color, scale it up, and then set it to only render faces that are "pointed in the wrong direction" - for us that means setting side:THREE.BackSide in the material. Eg here https://stemkoski.github.io/Three.js/Outline.html
But see what happens for me
Here's what I'd like to make
I have a bunch of objects that are close together - they get "inside" one another's outline.
Any advice on what I should do? What I want to be seeing is everywhere on the rendered frame that these shapes touch the background or each other, there you have outline.
What do you want to happen? Is that one mesh in your example or is it a bunch of intersecting meshes. If it's a bunch of intersecting meshes do you want them to have one outline? What about other meshes? My point is you need some way to define which "groups" of meshes get a single outline if you're using multiple meshes.
For multiple meshes and one outline a common solution is to draw all the meshes in a single group to a render target to generate a silhouette, then post process the silhouette to expand it. Finally apply the silhouette to the scene. I don't know of a three.js example but the concept is explained here and there's also many references here
Another solution that might work, should be possible to move the outline shell back in Z so doesn't intersect. Either all the way back (Z = 1 in clip space) or back some settable amount. Drawing with groups so that a collection of objects in front has an outline that blocks a group behind would be harder.
For example if I take this sample that prisoner849 linked to
And change the vertexShaderChunk in OutlineEffect.js to this
var vertexShaderChunk = `
#include <fog_pars_vertex>
uniform float outlineThickness;
vec4 calculateOutline( vec4 pos, vec3 objectNormal, vec4 skinned ) {
float thickness = outlineThickness;
const float ratio = 1.0; // TODO: support outline thickness ratio for each vertex
vec4 pos2 = projectionMatrix * modelViewMatrix * vec4( skinned.xyz + objectNormal, 1.0 );
// NOTE: subtract pos2 from pos because BackSide objectNormal is negative
vec4 norm = normalize( pos - pos2 );
// ----[ added ] ----
// compute a clipspace value
vec4 pos3 = pos + norm * thickness * pos.w * ratio;
// do the perspective divide in the shader
pos3.xyz /= pos3.w;
// just return screen 2d values at the back of the clips space
return vec4(pos3.xy, 1, 1);
}
`;
It's easier to see if you remove all references to reflectionCube and set the clear color to white renderer.setClearColor( 0xFFFFFF );
Original:
After:
I've been using Dgame framework for simple simulations.
I need moving object to be aligned to their velocity vectors.
How is it possible to do that using Dgame?
I see that shape object has setRotation and setRotationCenter. Not sure how to use these to achieve the effect. I realize that default is rotation around origin. This causes objects to drift over time.
Sample code
struct GameObject {
Point **position;
// array of pointers to object points
Point *acceleration;
Point *velocity;
double max_speed;
double max_force;
}
shape = new Shape(Geometry.Quads,
Vertex(object.position[0].x, object.position[0].y),
Vertex(object.position[1].x, object.position[1].y),
Vertex(object.position[2].x, object.position[2].y),
Vertex(object.position[3].x, object.position[3].y))
// rotate shape to face velocity here
shape.move(object.velocity.x, object.velocity.y);
You can achieve this using atan2. Depending on the orientation of the texture you might need to change the values a bit or add 90/-90 degrees.
For textures that face up:
rotation = atan2(-velocity.x, velocity.y);
For textures that face right:
rotation = atan2(-velocity.y, -velocity.x);
You might need to convert the result from radians to degrees or the other way around.
I have a problem with creating 3D cylinders (without OpenGL). I understand that a mesh is used to create the cylinder surface and triangle fans are used to create the top and bottom caps. I have already implemented the mesh but not the planar triangle fans, so currently my 3D object looks like a cylinder without the bottom and top cap.
I believe this is what I need to do in order to create the bottom and top caps. First, find the center point of the cylinder mesh. Second, find the vertices of the mesh. Third, using the center point and the 2 vertex points, create the triangle. Fourth, repeat the steps until a planar circle is created.
Are the above steps a sufficient way of creating the caps or is there a better way? And how do I find the vertices of the mesh so I can create the triangle fans?
First some notes:
you did not specify your platform
gfx interface
language
not enough info about your cylinder either
is it axis aligned?
what coordinate system (Cartesian/orthogonal/orthonormal)?
need additional dimensions like color or texture coordinates?
So I can provide just generic info then
Axis aligned cylinder
choose the granularity N
number of points along your cap's circle
usually 20-36 is OK but if you need higher precision then sometimes you need even 1000 points or more
all depends on the purpose,zoom, angle and distance of view ...
and performance issues
for now let N=32
you need BR (boundary representation)
you did not specify gfx interface but your text implies BR model (surface polygons)
also no pivot point position so I will choose middle point of cylinder to be (0,0,0)
z axis will be the height of cylinder
and the caps will be coplanar with xy plane
so for cylinder is enough set of 2 rings (caps)
so the points can be defined in C++ like this:
const int N=32; // mesh complexity
double p0[N][3],p1[N][3]; // rings`
double a,da,c,s,r,h2; // some temp variables
int i;
r =50.0; // cylinder radius
h2=100.0*0.5; // half height of cyliner
da=M_PI/double(N-1);
for (a=0.0,i=0;i<N;i++,a+=da)
{
c=r*cos(a);
s=r*sin(a);
p0[i][0]=c;
p0[i][1]=s;
p0[i][2]=+h2;
p1[i][0]=c;
p1[i][1]=s;
p1[i][2]=-h2;
}
the ring points are as closed loop (p0[0]==p0[N-1])
so you do not need additional lines to handle it...
now how to draw
cant write the code for unknown api but
'mesh' is something like QUAD_STRIP I assume
so just add points to it in this order:
QUAD_STRIP = { p0[0],p1[0],p0[1],p1[1],...p0[N-1],p1[N-1] };
if you have inverse normal problem then swap p0/p1
now for the fans
you do not need the middle point (unless you have interpolation aliasing issues)
so similar:
TRIANGLE_FAN0 = { p0[0],p0[1],...p0[N-1] };
TRIANGLE_FAN1 = { p1[0],p1[1],...p1[N-1] };
if you still want the middle point then:
TRIANGLE_FAN0 = { (0.0,0.0,+h2),p0[0],p0[1],...p0[N-1] };
TRIANGLE_FAN1 = { (0.0,0.0,-h2),p1[0],p1[1],...p1[N-1] };
if you have inverse normal problem then reverse the points order (middle point stays where it is)
Not axis aligned cylinder?
just use transform matrix on your p0[],p1[] point lists to translate/rotate to desired position
the rest stays the same
we are programming a 2D game in XNA. Now we have polygons which define our level elements. They are triangulated such that we can easily render them. Now I would like to write a shader which renders the polygons as outlined textures. So in the middle of the polygon one would see the texture and on the border it should somehow glow.
My first idea was to walk along the polygon and draw a quad on each line segment with a specific texture. This works but looks strange for small corners where the textures are forced to overlap.
My second approach was to mark all border vertices with some kind of normal pointing out of the polygon. Passing this to the shader would interpolate the normals across edges of the triangulation and I could use the interpolated "normal" as a value for shading. I could not test it yet but would that work? A special property of the triangulation is that all vertices are on the border so there are no vertices inside the polygon.
Do you guys have a better idea for what I want to achieve?
Here A picture of what it looks right now with the quad solution:
You could render your object twice. A bigger stretched version behind the first one. Not that ideal since a complex object cannot be streched uniformly to create a border.
If you have access to your screen buffer you can render your glow components into a rendertarget and align a full-screen quad to your viewport and add a fullscreen 2D silhouette filter to it.
This way you gain perfect control over the edge by defining its radius, colour, blur. With additional output values such as the RGB values from the object render pass you can even have different advanced glows.
I think rendermonkey had some examples in their shader editor. Its definetly a good starting point to work with and try out things.
Propaply you want calclulate new border vertex list (easy fill example with triangle strip with originals). If you use constant border width and convex polygon its just:
B_new = B - (BtoA.normalised() + BtoC.normalised()).normalised() * width;
If not then it can go more complicated, there is my old but pretty universal solution:
//Helper function. To working right, need that v1 is before v2 in vetex list and vertexes are going to (anti???) cloclwise!
float vectorAngle(Vector2 v1, Vector2 v2){
float alfa;
if (!v1.isNormalised())
v1.normalise();
if (!v2.isNormalised())
v2.normalise();
alfa = v1.dotProduct(v2);
float help = v1.x;
v1.x = v1.y;
v1.y = -help;
float angle = Math::ACos(alfa);
if (v1.dotProduct(v2) < 0){
angle = -angle;
}
return angle;
}
//Normally dont use directly this!
Vector2 calculateBorderPoint(Vector2 vec1, Vector2 vec2, float width1, float width2){
vec1.normalise();
vec2.normalise();
float cos = vec1.dotProduct(vec2); //Calculates actually cosini of two (normalised) vectors (remember math lessons)
float csc = 1.0f / Math::sqrt(1.0f-cos*cos); //Calculates cosecant of angle, This return NaN if angle is 180!!!
//And rest of the magic
Vector2 difrence = (vec1 * csc * width2) + (vec2 * csc * width1);
//If you use just convex polygons (all angles < 180, = 180 not allowed in this case) just return value, and if not you need some more magic.
//Both of next things need ordered vertex lists!
//Output vector is always to in side of angle, so if this angle is.
if (Math::vectorAngle(vec1, vec2) > 180.0f) //Note that this kind of function can know is your function can know that angle is over 180 ONLY if you use ordered vertexes (all vertexes goes always (anti???) cloclwise!)
difrence = -difrence;
//Ok and if angle was 180...
//Note that this can fix your situation ONLY if you use ordered vertexes (all vertexes goes always (anti???) cloclwise!)
if (difrence.isNaN()){
float width = (width1 + width2) / 2.0; //If angle is 180 and border widths are difrent, you cannot get perfect answer ;)
difrence = vec1 * width;
//Just turn vector -90 degrees
float swapHelp = difrence.y
difrence.y = -difrence.x;
difrence.x = swapHelp;
}
//If you don't want output to be inside of old polygon but outside, just: "return -difrence;"
return difrence;
}
//Use this =)
Vector2 calculateBorderPoint(Vector2 A, Vector2 B, Vector2 C, float widthA, float widthB){
return B + calculateBorderPoint(A-B, C-B, widthA, widthB);
}
Your second approach can be possible...
mark the outer vertex (in border) with 1 and the inner vertex (inside) with 0.
in the pixel shader you can choose to highlight, those that its value is greater than 0.9f or 0.8f.
it should work.