#include "ofApp.h"
#include "glew.h"


//--------------------------------------------------------------
void ofApp::setup(){

}



//--------------------------------------------------------------
void ofApp::update(){

	
}

void gaussianElimination(float * input, int n)
{
	auto i = 0;
	auto j = 0;
	auto m = n - 1;

	while (i < m && j < n) 
	{
		auto iMax = i;
		for (auto k = i + 1; k < m; ++k)
		{
			if (fabs(input[k * n + j]) > fabs(input[iMax * n + j])) 
			{
				iMax = k;
			}
		}

		if (input[iMax * n + j] != 0) 
		{
			if (i != iMax)
			{
				for (auto k = 0; k < n; ++k)
				{
					auto ikIn = input[i * n + k];
					input[i * n + k] = input[iMax * n + k];
					input[iMax * n + k] = ikIn;
				}
			}

			float ijIn = input[i * n + j];
			for (auto k = 0; k < n; ++k)
			{
				input[i * n + k] /= ijIn;
			}

			for (auto u = i + 1; u < m; ++u)
			{
				auto ujIn = input[u * n + j];
				for (auto k = 0; k < n; ++k)
				{
					input[u * n + k] -= ujIn * input[i * n + k];
				}
			}

			++i;
		}
		++j;
	}

	for (auto i = m - 2; i >= 0; --i)
	{
		for (auto j = i + 1; j < n - 1; ++j)
		{
			input[i * n + m] -= input[i * n + j] * input[j * n + m];
		}
	}
}

glm::mat4 getPerspectiveTransformMatrix(const glm::vec2 src[4], const glm::vec2 dst[4])
{
	float p[8][9] = 
	{
		{ -src[0][0], -src[0][1], -1, 0, 0, 0, src[0][0] * dst[0][0], src[0][1] * dst[0][0], -dst[0][0] }, // h11
		{ 0, 0, 0, -src[0][0], -src[0][1], -1, src[0][0] * dst[0][1], src[0][1] * dst[0][1], -dst[0][1] }, // h12
		{ -src[1][0], -src[1][1], -1, 0, 0, 0, src[1][0] * dst[1][0], src[1][1] * dst[1][0], -dst[1][0] }, // h13
		{ 0, 0, 0, -src[1][0], -src[1][1], -1, src[1][0] * dst[1][1], src[1][1] * dst[1][1], -dst[1][1] }, // h21
		{ -src[2][0], -src[2][1], -1, 0, 0, 0, src[2][0] * dst[2][0], src[2][1] * dst[2][0], -dst[2][0] }, // h22
		{ 0, 0, 0, -src[2][0], -src[2][1], -1, src[2][0] * dst[2][1], src[2][1] * dst[2][1], -dst[2][1] }, // h23
		{ -src[3][0], -src[3][1], -1, 0, 0, 0, src[3][0] * dst[3][0], src[3][1] * dst[3][0], -dst[3][0] }, // h31
		{ 0, 0, 0, -src[3][0], -src[3][1], -1, src[3][0] * dst[3][1], src[3][1] * dst[3][1], -dst[3][1] }, // h32
	};

	gaussianElimination(&p[0][0], 9);

	return glm::mat4(p[0][8], p[3][8], 0, p[6][8], 
					 p[1][8], p[4][8], 0, p[7][8], 
					 0, 0, 1, 0, 
					 p[2][8], p[5][8], 0, 1);
}

ofPolyline ofApp::polyLineTransform(const ofPolyline& poly, ofMatrix4x4 xform){
	ofPolyline tempPoly;
	for (auto& p:poly){
		tempPoly.addVertex(ofVec3f(p)*xform);
	}
	return tempPoly;
}

ofPolyline makePolygon(int num,float diam){
	ofPolyline poly;
	float step=PI*2/num;
	for (int i=0;i<=num;i++){
		poly.addVertex(cos(step*i)*diam,sin(step*i)*diam);
	}
	return poly;
}

void drawPoly(ofPolyline poly,float x,float y){
	glPushMatrix();
	ofTranslate(x,y);
	poly.draw();
	for (int i=0;i<poly.size();i++){
		ofDrawBitmapString(poly.getDegreesAtIndex(i),poly[i].x+10,poly[i].y+10,0);
	}
	glPopMatrix();
}


//--------------------------------------------------------------	
void ofApp::draw(){
	ofBackground(0,0,0);
	ofSetColor(255,255,255);

	ofMatrix4x4 m = ofMatrix4x4::newIdentityMatrix();
    m.rotateRad(ofGetElapsedTimef(),0,0,1);
    m.translate(ofGetWidth()/2,ofGetHeight()/2,0);

    glm::vec2 src[]={
    	glm::vec2(0,0),
    	glm::vec2(ofGetWidth(),0),
    	glm::vec2(ofGetWidth(),ofGetHeight()),
    	glm::vec2(0,ofGetHeight())
    };

    glm::vec2 dst[]={
    	glm::vec2(0,0),
    	glm::vec2(ofGetWidth(),0),
    	glm::vec2(ofGetWidth()-100,ofGetHeight()),
    	glm::vec2(100,ofGetHeight())
    };

    ofMatrix4x4 warp =getPerspectiveTransformMatrix(src,dst);

    //drawPoly(polyLineTransform(makePolygon(4,200),m),200,200);
    //drawPoly(polyLineTransform(makePolygon(5,200),m),-200,200);
    //drawPoly(polyLineTransform(makePolygon(6,200),m),-200,-200);

    drawPoly(polyLineTransform(polyLineTransform(makePolygon(6,200),m),warp),0,0);


}


//--------------------------------------------------------------
void ofApp::exit() {
	
}



//--------------------------------------------------------------
void ofApp::keyPressed(ofKeyEventArgs &args){



}


//--------------------------------------------------------------
void ofApp::keyReleased(int key){

	
}

//--------------------------------------------------------------
void ofApp::mouseMoved(int x, int y ){

}

//--------------------------------------------------------------
void ofApp::mouseDragged(int x, int y, int button){
	
}

//--------------------------------------------------------------
void ofApp::mousePressed(int x, int y, int button){
	
}

//--------------------------------------------------------------
void ofApp::mouseReleased(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mouseEntered(int x, int y){

}

//--------------------------------------------------------------
void ofApp::mouseExited(int x, int y){

}

//--------------------------------------------------------------
void ofApp::windowResized(int w, int h){

}

void ofApp::outputWindowResized(ofResizeEventArgs &resizeargs){

}

//--------------------------------------------------------------
void ofApp::gotMessage(ofMessage msg){

}

//--------------------------------------------------------------
void ofApp::dragEvent(ofDragInfo dragInfo){ 

	
}