objective-c isgl3d 反射线拾取

来源：互联网发布：golang os.exit 编辑：程序博客网时间：2024/06/06 14:59

http://softwareprodigy.blogspot.com/2009/08/gluunproject-for-iphone-opengl-es.html

//-(CGPoint) getOGLPos:(CGPoint)winPos

//{

// // I am doing this once at the beginning when I set the perspective view

// glGetFloatv( GL_MODELVIEW_MATRIX, __modelview );

// glGetFloatv( GL_PROJECTION_MATRIX, __projection );

// glGetIntegerv( GL_VIEWPORT, __viewport );

// //opengl 0,0 is at the bottom not at the top

// winPos.y = (float)__viewport[3] - winPos.y;

// // float winZ;

// //we cannot do the following in openGL ES due to tile rendering

// // glReadPixels( (int)winPos.x, (int)winPos.y, 1, 1, GL_DEPTH_COMPONENT24_OES, GL_FLOAT, &winZ );

// float cX, cY, cZ, fX, fY, fZ;

// //gives us camera position (near plan)

// gluUnProject( winPos.x, winPos.y, 0, __modelview, __projection, __viewport, &cX, &cY, &cZ);

// //far plane

// gluUnProject( winPos.x, winPos.y, 1, __modelview, __projection, __viewport, &fX, &fY, &fZ);

// //We could use some vector3d class, but this will do fine for now

// //ray

// fX -= cX;

// fY -= cY;

// fZ -= cZ;

// float rayLength = sqrtf(cX*cX + cY*cY + cZ*cZ);

// //normalize

// fX /= rayLength;

// fY /= rayLength;

// fZ /= rayLength;

// //T = [planeNormal.(pointOnPlane - rayOrigin)]/planeNormal.rayDirection;

// //pointInPlane = rayOrigin + (rayDirection * T);

// float dot1, dot2;

// float pointInPlaneX = 0;

// float pointInPlaneY = 0;

// float pointInPlaneZ = 0;

// float planeNormalX = 0;

// float planeNormalY = 0;

// float planeNormalZ = -1;

// pointInPlaneX -= cX;

// pointInPlaneY -= cY;

// pointInPlaneZ -= cZ;

// dot1 = (planeNormalX * pointInPlaneX) + (planeNormalY * pointInPlaneY) + (planeNormalZ * pointInPlaneZ);

// dot2 = (planeNormalX * fX) + (planeNormalY * fY) + (planeNormalZ * fZ);

// float t = dot1/dot2;

// fX *= t;

// fY *= t;

// //we don't need the z coordinate in my case

// return CGPointMake(fX + cX, fY + cY);

//}

别人源码，摘来分享，哈哈哈

CGPoint startLocation;

-(void ) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

{

NSLog(@"touches begin!!");

NSEnumerator * enumerator = [touchesobjectEnumerator];

UITouch * touch1 = [enumeratornextObject];

startLocation = [m_pViewconvertUIPointToView:[touch1locationInView:touch1.view]];

// glGetFloatv( GL_MODELVIEW_MATRIX, __modelview );

// glGetFloatv( GL_PROJECTION_MATRIX, __projection );

// glGetIntegerv( GL_VIEWPORT, __viewport );

Isgl3dMatrix4 modelView =m_pView.scene.worldTransformation;

Isgl3dMatrix4 projectiveMatrix =m_pView.camera.viewProjectionMatrix;

CGRect viewPort =m_pView.viewport;

float moV[16];

// for( int i =0 ; i < 16 ; i++)

{

moV[0] = modelView.sxx;

moV[1] = modelView.syx;

moV[2] = modelView.szx;

moV[3] = modelView.swx;

moV[4] = modelView.sxy;

moV[5] = modelView.syy;

moV[6] = modelView.szy;

moV[7] = modelView.swy;

moV[8] = modelView.sxz;

moV[9] = modelView.syz;

moV[10] = modelView.szz;

moV[11] = modelView.swz;

moV[12] = modelView.tx;

moV[13] = modelView.ty;

moV[14] = modelView.tz;

moV[15] = modelView.tw;

}

float pV[16];

{

pV[0] = projectiveMatrix.sxx;

pV[1] = projectiveMatrix.syx;

pV[2] = projectiveMatrix.szx;

pV[3] = projectiveMatrix.swx;

pV[4] = projectiveMatrix.sxy;

pV[5] = projectiveMatrix.syy;

pV[6] = projectiveMatrix.szy;

pV[7] = projectiveMatrix.swy;

pV[8] = projectiveMatrix.sxz;

pV[9] = projectiveMatrix.syz;

pV[10] = projectiveMatrix.szz;

pV[11] = projectiveMatrix.swz;

pV[12] = projectiveMatrix.tx;

pV[13] = projectiveMatrix.ty;

pV[14] = projectiveMatrix.tz;

pV[15] = projectiveMatrix.tw;

}

int vP[4];

vP[0] = viewPort.origin.x;

vP[1] = viewPort.origin.y;

vP[2] = viewPort.size.width;

vP[3] = viewPort.size.height;

float result[3];

//gives us camera position (near plan)

glhUnProjectf(startLocation.x,startLocation.y, 0, moV, pV, vP, result);

fPoint3 start;

start.x = result[0];

start.y = result[1];

start.z = result[2];

//far plane

glhUnProjectf(startLocation.x,startLocation.y, 1, moV, pV, vP, result);

fPoint3 end;

end.x = result[0];

end.y = result[1];

end.z = result[2];

//射线求交点（与地面（x, y, 0））

getCrossPoint(start, end,wordStart);

//。。。。

wordEnd.x =wordStart.x;

wordEnd.y =wordStart.y;

wordEnd.z =wordStart.z;

}

int glhUnProjectf(float winx,float winy,float winz,float *modelview,float *projection,int *viewport, float *objectCoordinate)

{

//Transformation matrices

float m[16], A[16];

float in[4], out[4];

//float B[16];

//Calculation for inverting a matrix, compute projection x modelview

//and store in A[16]

MultiplyMatrices4by4OpenGL_FLOAT(A, projection, modelview);

//Now compute the inverse of matrix A

if(glhInvertMatrixf2(A, m)==0)

return 0;

//Transformation of normalized coordinates between -1 and 1

in[0]=(winx-(float)viewport[0])/(float)viewport[2]*2.0-1.0;

in[1]=(winy-(float)viewport[1])/(float)viewport[3]*2.0-1.0;

in[2]=2.0*winz-1.0;

in[3]=1.0;

//Objects coordinates

MultiplyMatrixByVector4by4OpenGL_FLOAT(out, m,in);

if(out[3]==0.0)

return 0;

out[3]=1.0/out[3];

objectCoordinate[0]=out[0]*out[3];

objectCoordinate[1]=out[1]*out[3];

objectCoordinate[2]=out[2]*out[3];

return 1;

}

//用来求取直线和地图平面的交点

bool getCrossPoint(fPoint3 startPoint,fPoint3 endPoint,fPoint3 &CrossPoint ){

if(startPoint.z==endPoint.z)returnfalse;//没有交点

float v0=endPoint.x-startPoint.x;

float v1=endPoint.y-startPoint.y;

float v2=endPoint.z-startPoint.z;

float t= - startPoint.z/v2;

//求取交点

CrossPoint.x=v0*t+startPoint.x;

CrossPoint.y=v1*t + startPoint.y;

CrossPoint.z=0;

returntrue;

}