Lensflare

void DrawLensFlare(){	//Get vector between light source and camera	Vector3D cameraLight;	cameraLight.x = aLight.position[0] - aCamera->mPos.x;	cameraLight.y = aLight.position[1] - aCamera->mPos.y;	cameraLight.z = aLight.position[2] - aCamera->mPos.z;	float cameraLightLength = sqrt(pow(cameraLight.x,2) + pow(cameraLight.y,2) + pow(cameraLight.z,2));	//Normalise the vector	cameraLight.x /= cameraLightLength;	cameraLight.y /= cameraLightLength;	cameraLight.z /= cameraLightLength;    // Start of with a simple quad...    Vector3D vPoint0(-1.0, -1.0, 0.0f);    Vector3D vPoint1( 1.0, -1.0, 0.0f);    Vector3D vPoint2( 1.0,  1.0, 0.0f);    Vector3D vPoint3(-1.0,  1.0, 0.0f);		float lensScale = 5.5f;		//value by which we scale size of bitmap		float distance = 0.8f;		//the scale from the camera to the light source (ie 1.0 is at the camera, 0.0 is at the light)        // If billboarding is toggled on, recompute the quad points        // with respect to the view matrix and the quad's center point.        float mat[16];        glGetFloatv( GL_MODELVIEW_MATRIX, mat );		Vector3D vRight;   vRight.x = mat[0];     vRight.y = mat[4];     vRight.z = mat[8];		Vector3D vUp;      vUp.x = mat[1];        vUp.y = mat[5];        vUp.z = mat[9];		Vector3D vCentre;		//Enable shaders		// Bind and enable Our Vertex Program To The Current State and grab the modelview matrix		cgGLSetStateMatrixParameter(cgModelViewMatrix, CG_GL_MODELVIEW_PROJECTION_MATRIX, CG_GL_MATRIX_IDENTITY);		cgGLEnableProfile(cgLensFlareVertexProfile);		cgGLBindProgram(cgLensFlareVertexProgram);	   //Same for fragment shader	 cgGLBindProgram(cgLensFlareFragmentProgram);	  cgGLEnableProfile(cgLensFlareFragmentProfile);	  cgGLEnableTextureParameter(lensFlareTexture);for(int i = 0; i < 4; i++){	//Attatch the relevant lensflare texture	 cgGLSetTextureParameter(lensFlareTexture, lensFlare->texture);	distance /= 2;	vCentre.x = aLight.position[0] + (distance * cameraLight.x);	vCentre.y = aLight.position[1] + (distance * cameraLight.y);	vCentre.z = aLight.position[2] + (distance * cameraLight.z);	// Now, build a quad around the center point based on the vRight 	// and vUp vectors. This will guarantee that the quad will be 	// orthogonal to the view.	vPoint0 = vCentre + ((-vRight - vUp) * lensScale);	vPoint1 = vCentre + (( vRight - vUp) * lensScale);	vPoint2 = vCentre + (( vRight + vUp) * lensScale);	vPoint3 = vCentre + ((-vRight + vUp) * lensScale);		glEnable(GL_TEXTURE_2D);		glEnable(GL_BLEND);		glDisable(GL_DEPTH_TEST);	// Turn Depth Testing Off		glColor4f(1.0f,0.0f,1.0f,0.5f);					glBlendFunc(GL_SRC_ALPHA,GL_ONE);		// Blending Function For Translucency Based On Source Alpha Value ( NEW )		glBegin( GL_QUADS );		{			glTexCoord2f(0.0f, 0.0f);			glVertex3f(vPoint0.x,vPoint0.y,vPoint0.z);			glTexCoord2f(1.0f, 0.0f);			glVertex3f(vPoint1.x, vPoint1.y,vPoint1.z);			glTexCoord2f(1.0f, 1.0f);			glVertex3f(vPoint2.x,vPoint2.y,vPoint2.z);			glTexCoord2f(0.0f, 1.0f);			glVertex3f(vPoint3.x,vPoint3.y,vPoint3.z);		}		glEnd();		glDisable(GL_BLEND);			  }	//Turn off shaders	  cgGLDisableProfile(cgLensFlareVertexProfile);	//Disable vertex shader	  cgGLDisableProfile(cgLensFlareFragmentProfile);			//Disable fragment shade	  cgGLDisableTextureParameter(lensFlareTexture);			//Disable textures}