## triangle

### Find the last co-ordinate of isosceles triangle given coordinates of base and altitude.

Hi, I have no clue about trigonometry, despite learning it in school way back when, and I figure this should be pretty straightforward, but trawling through tons of trig stuff on the web makes my head hurt :) So maybe someone could help me... The title explains exactly what I want to do, I have a line: x1,y1 and x2,y2 and want a funct...

### finding center of 2D triangle

(Yes, unfortunately, this is a homework question) I've been given a struct for a 2D triangle with x and y coordinates, a rotation variable, and so on. From the point created by those x and y coordinates, I am supposed to draw a triangle around the point and rotate it appropriately using the rotation variable. I'm familiar with drawing...

### Yellow Triangle that should be 3 colours OpenGL

This is probably a silly mistake but I cant see it?! I have classes defining geometry and classes that render that geometry. Right now it is basic triangles and colours for each vertex. Here is the code defining said geometry objects data: CGeometry* g = new CGeometry(); g->vertexes = new double[3*3]; g->vertexes[0] = 0; g->vertexes[...

### How to fill color on triangle

Hi everyone, I draw a triangle using line. How can I fill color on it? So far I can only success color the line but not fill the color. public void paintComponent(Graphics g){ super.paintComponents(g); int k=0; for (j=0 ; j < numOfLines; j++){ // the values of numOfLines retrieved from other method. g....

### How to sort a bunch of polygons/polyhedra by a specific value at their vertices (or some other distance measure)

I am working on a project which will be using large datasets (both 2D and 3D) which I will be turning into triangles, or tetrahedra, in order to render them. I will also be performing calculations on these tris/tets. Which tris/tets to use for each calculation depend on the greatest and smallest values of their vertices. So I need to ...

### OpenGL: Fastest way to draw a mixture of triangles and quads?

I have a mesh data structure with polygons that can be either triangles and quads. What is the fastest way to draw this using OpenGL? The slow way is to iterate over the structure and for each polygon to make the appropriate glBegin() .. glEnd() with either GL_QUADS or GL_TRIANGLES. I would like to avoid having to do glBegin() .. glEn...

### Determine if a 3D point is within a triangle

Given a 3D point (x, y & z), and a triangle made of three other 3D points, how can I determine if the point is in triangle? I've read a lot about doing this in 2D, the most helpful being http://imusthaveit.spaces.live.com/blog/cns!B5212D3C9F7D8093!410.entry, but I'm struggling to move the concept to 3D - could anyone help with either th...

### What controls the behavior of OpenGL when drawing triangle strips?

So I do know how to draw multiple triangles using glBegin(GL_TRIANGLE_STRIPS). What I want to understand is how OpenGL decides which vertex (out of the first three provided) to use as the starting vertex for all remaining triangles to be drawn? And is there a way to make it select a different starting vertex? ...

### Display triangles in 3D using Python

Disclaimer: The context is a project I'm working on as part of my Master's degree. I guess it qualifies as homework. Introduction (feel free to skip to the bottom line) Curved 3D surfaces are commonly displayed as a large set of very small triangles. Each triangle has the following properties: 3 corners uniform color Such tha...

### using + and - or triangle pointing to the right or down?

I've seen web sites that use the MS convention of using the "+" (plus) and "-" (minus) sign to expand and collapse rows of folders. On other web sites I've seen the Macintosh style of using the little triangle (arrow) pointing to the right to show a collapsed row (nested folder) and pointing down to represent a folder that has been expan...

### How to calculate the volume of a 3D mesh object the surface of which is made up triangles

Hello Friends, I want to calculate the volume of a 3D mesh object having a surface made up triangles. Could you help me. Thank in advance Best Regards. Can ...

### Triangle Triangle Intersection On 3d Sapace

Hi, Now i m Working on 3d . In that I need to find intersection of triangle with other triangle. How to find it. Please Help. ...

### How to plot triangles on a 6x6 grid in MATLAB?

I have a file a.txt which is like: 0 0 0 3 4 3 0 0 3 0 3 4 0 1 0 4 4 4 0 1 3 1 3 5 0 2 0 5 4 5 0 3 0 0 4 0 These are vertices of triangles [x1 y1 x2 y2 x3 y3] that I need to plot on a 6x6 grid. I need to see these triangles on a single graph. How can this be done in MATLAB? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~...

### 2D Triangle in SlimDX

How to draw a triangle using SlimDX's Direct2D interface given triangle vertices are given in pixel coordinates? ...

### how to differentiate between circle rectangle and triangle ?

sorry but i need help how to differentiate between circle rectangle and triangle in black and white images-bitmaps- ...

### finding cycle of 3 nodes ( or triangles) in a graph

hi all, i am working with complex networks. I want to find group of nodes which forms cycle of 3 nodes ( or triangles) in a given graph. As my graph contains about million edges, so the use simple iterative (multiple "for" loop) is not very efficient. If someone knows any algorithm which can be used for finding triangles in graphs, kind...

### Creating a surface of triangles from a set of 2D points...

Hi, I have a set of points and I need to convert the set to (non-overlapping) triangles (or a big polygon if equivalent)... The application: I have a list of locations (latitude,longitude) from a country, and I need to find if a given point is inside the counrty or not... X X *---------* ...

### Line segment in a triangle

Hi All, How can we check if a line segment falls partially or fully inside a triangle? Cheers. ...

### C++ Pascal's triangle

Hello, I'm looking for an explanation for how the recursive version of pascal's triangle works The following is the recursive return line for pascal's triangle. int get_pascal(const int row_no,const int col_no) { if (row_no == 0) { return 1; } else if (row_no == 1) { return 1; } else if (col...

### Normal of an equilateral triangle that has been arbitrarily transformed in 3D space

I have an issue that I can't quite seem to find a starting point on; I'm not even sure I can describe it well enough to get an answer. I need to find the normal of an equilateral triangle in 3D space without knowing the points of the triangle beforehand. Think about taking a photo of a triangular "yield" street sign from any angle, and...