---

selection.h File Reference

#include <windows.h>
#include "polygon.h"

Go to the source code of this file.

Functions
int	SelectPolygon (HWND hWnd, POLYGON *Polygons, int numPolys, int MouseX, int MouseY)

---

Function Documentation

int SelectPolygon (  HWND    hWnd, POLYGON *    Polygons, int    numPolys, int    MouseX, int    MouseY )

Definition at line 19 of file selection.cpp. References CheckClipPlanes(), CheckPointInTriangle(), VERTEX::coords, currentCamera, VECTOR::GetMagnitude(), line_plane_collision(), MouseX, MouseY, VERTEX::normal, POLYGON::numVertices, POLYGON::Vertex, VECTOR::x, VECTOR::y, and VECTOR::z. Referenced by WndProc(). { POLYGON tempPolygon; VECTOR CollisionPoint, p0, pN, a, b, c; int tempPolygonNumber; // Returned index VECTOR tempVect; float Distance; VERTEX tempVertex; VECTOR WorldPos; float ShortestDistance = 10000000; // Set to an initial distance further than all polygons bool flag = false; // Flag indicating intersection status // Temporary variables for polygon tessellation int numNewPolygons = 0; POLYGON newPolygon[30]; // Get the modelview and projection matrices double WorldPosX, WorldPosY, WorldPosZ, MousePosX, MousePosY, MousePosZ; double ModelMatrix[16]; glGetDoublev(GL_MODELVIEW_MATRIX, ModelMatrix); double ProjMatrix[16]; glGetDoublev(GL_PROJECTION_MATRIX, ProjMatrix); // Get the current viewport int Viewport[4]; glGetIntegerv(GL_VIEWPORT, Viewport); if (MouseX >= Viewport[0] && MouseX <= Viewport[2] && MouseY >= Viewport[1] && MouseY <= Viewport[3]) { // Set the end point of ray in windows coordinates MousePosX = MouseX; MousePosY = Viewport[3] - MouseY; // invert mouse Y coordinate MousePosZ = 0.5; // near clip plane depth // Get unprojected end point gluUnProject ( MousePosX, MousePosY, MousePosZ, ModelMatrix, ProjMatrix, Viewport, &WorldPosX, &WorldPosY, &WorldPosZ ); WorldPos.x = WorldPosX; WorldPos.y = WorldPosY; WorldPos.z = WorldPosZ; // Check for line polygon collision with all polygons for (int outerloop = 0; outerloop < numPolys; outerloop++) { // Make a copy of the polygon to work with tempPolygon.Vertex[0] = Polygons[outerloop].Vertex[0]; tempPolygon.Vertex[1] = Polygons[outerloop].Vertex[1]; tempPolygon.Vertex[2] = Polygons[outerloop].Vertex[2]; tempPolygon.numVertices = Polygons[outerloop].numVertices; // Get a point on the polygon p0 = tempPolygon.Vertex[0].coords; // Get the polygons normal pN = tempPolygon.Vertex[0].normal; // Find collision point on the plane CollisionPoint = line_plane_collision(&camera[currentCamera].Position, &WorldPos, &tempPolygon); // If the collision point is outside the frustum (indicating a collision behind the camera) then continue if (!CheckClipPlanes(camera[currentCamera], CollisionPoint)) // Function is in the general.cpp source file continue; // Subdivide polygon into new polygons numNewPolygons = 0; for (int innerloop = 2; innerloop < tempPolygon.numVertices; innerloop++) { numNewPolygons++; newPolygon[innerloop - 2].Vertex[0] = tempPolygon.Vertex[0]; newPolygon[innerloop - 2].Vertex[1] = tempPolygon.Vertex[innerloop - 1]; newPolygon[innerloop - 2].Vertex[2] = tempPolygon.Vertex[innerloop]; } // If collision point is within the polygon for (int innerloop = 0; innerloop < numNewPolygons; innerloop++) { a = newPolygon[innerloop].Vertex[0].coords; b = newPolygon[innerloop].Vertex[1].coords; c = newPolygon[innerloop].Vertex[2].coords; if (CheckPointInTriangle(CollisionPoint, a, b, c)) // Function is in the collision.cpp source file { // Find distance to the collision point tempVect = CollisionPoint - camera[currentCamera].Position; Distance = tempVect.GetMagnitude(); // If this intersection is closest if (Distance < ShortestDistance) { tempPolygonNumber = outerloop; ShortestDistance = Distance; flag = true; } } } } if (flag) return tempPolygonNumber; else return -1; } }

---