『openframeworks』shader制作六边形马赛克效果 http://blog.csdn.net/simpledrunk/article/details/17095821

hexagon mosaic

//testApp.h
#pragma once

#include "ofMain.h"

class testApp : public ofBaseApp{

public:
	void setup();
	void update();
	void draw();

	void keyPressed  (int key);
	void keyReleased(int key);
	void mouseMoved(int x, int y );
	void mouseDragged(int x, int y, int button);
	void mousePressed(int x, int y, int button);
	void mouseReleased(int x, int y, int button);
	void windowResized(int w, int h);
	void dragEvent(ofDragInfo dragInfo);
	void gotMessage(ofMessage msg);

	ofImage img;
	ofShader shader;
	ofFbo fbo;

	float len;
	bool bAdd;
};



//testApp.cpp
#include "testApp.h"

//--------------------------------------------------------------
void testApp::setup(){
	img.loadImage("bg.jpg");

	fbo.allocate(640, 480);

	shader.load("hexagon.vert", "hexagon.frag");
	len = 8.0f;
	bAdd = false;
}

//--------------------------------------------------------------
void testApp::update(){
	if(len < 10.0f)
		bAdd = true;
	if(len > 20.0f)
		bAdd = false;
	len += bAdd ? (0.005f):(-0.005f);
}

//--------------------------------------------------------------
void testApp::draw(){
	ofEnableAlphaBlending();
	img.draw(0, 0, 640, 480);

	fbo.begin();
	img.draw(0, 0, 640, 480);
	fbo.end();

	shader.begin();
	shader.setUniform1f("len", len);
	shader.setUniformTexture("colorTex0", fbo.getTextureReference(), 0);
	fbo.draw(0, 0, 640, 480);
	shader.end();

	ofDisableAlphaBlending();
}

//--------------------------------------------------------------
void testApp::keyPressed(int key){

}

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

}

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

}

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

}

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

}

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

}

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

}

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

}

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

}

//hexagon.frag
#version 400
#extension GL_ARB_texture_rectangle : enable

uniform float len;
uniform sampler2DRect colorTex0;
void main (void){
	float TR = 0.866025f;
	float x = gl_TexCoord[0].x;
	float y = gl_TexCoord[0].y;
	int wx = int(x/1.5f/len);
	int wy = int(y/TR/len);
	vec2 v1, v2, vn;
	if(wx/2 * 2 == wx) {
		if(wy/2 * 2 == wy) {
				v1 = vec2(len*1.5f*wx, len*TR*wy);
				v2 = vec2(len*1.5f*(wx+1), len*TR*(wy+1));
			} else {
				v1 = vec2(len*1.5f*wx, len*TR*(wy+1));
				v2 = vec2(len*1.5f*(wx+1), len*TR*wy);
			}
		} else {
		if(wy/2 * 2 == wy) {
			v1 = vec2(len*1.5f*wx, len*TR*(wy+1));
			v2 = vec2(len*1.5f*(wx+1), len*TR*wy);
			} else {
				v1 = vec2(len*1.5f*wx, len*TR*wy);
				v2 = vec2(len*1.5f*(wx+1), len*TR*(wy+1));
			}
	}
	float s1 = sqrt( pow(v1.x-x, 2) + pow(v1.y-y, 2) );
	float s2 = sqrt( pow(v2.x-x, 2) + pow(v2.y-y, 2) );
	if(s1 < s2)
		vn = v1;
	else
		vn = v2;
	vec4  color = texture2DRect(colorTex0, vn);
	gl_FragColor = color;
}


//hexagon.vert
#version 400
#extension GL_ARB_texture_rectangle : enable

void main(){
	gl_TexCoord[0] = gl_MultiTexCoord0;
	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}

//三角形马赛克frag script
//triangle.frag

version 400

extension GL_ARB_texture_rectangle : enable

uniform float len;
uniform sampler2DRect colorTex0;
void main (void){
float TR = 0.866025f;
float PI6 = 0.523599f; //PI/12
float x = gl_TexCoord[0].x;
float y = gl_TexCoord[0].y;
int wx = int(x/1.5f/len);
int wy = int(y/TR/len);
vec2 v1, v2, vn;
if(wx/2 * 2 == wx) {
if(wy/2 * 2 == wy) {
v1 = vec2(len_1.5f_wx, len_TR_wy);
v2 = vec2(len_1.5f_(wx+1), len_TR_(wy+1));
} else {
v1 = vec2(len_1.5f_wx, len_TR_(wy+1));
v2 = vec2(len_1.5f_(wx+1), len_TR_wy);
}
} else {
if(wy/2 * 2 == wy) {
v1 = vec2(len_1.5f_wx, len_TR_(wy+1));
v2 = vec2(len_1.5f_(wx+1), len_TR_wy);
} else {
v1 = vec2(len_1.5f_wx, len_TR_wy);
v2 = vec2(len_1.5f_(wx+1), len_TR_(wy+1));
}
}
float s1 = sqrt( pow(v1.x-x, 2) + pow(v1.y-y, 2) );
float s2 = sqrt( pow(v2.x-x, 2) + pow(v2.y-y, 2) );
if(s1 < s2)
vn = v1;
else
vn = v2;
float a = atan((x-vn.x)/(y-vn.y));//夹角
vec2 area1 = vec2(vn.x, vn.y-len/TR/2);
vec2 area2 = vec2(vn.x+len/2, vn.y-len/TR/4);
vec2 area3 = vec2(vn.x+len/2, vn.y+len/TR/4);
vec2 area4 = vec2(vn.x, vn.y+len/TR/2);
vec2 area5 = vec2(vn.x-len/2, vn.y+len/TR/4);
vec2 area6 = vec2(vn.x-len/2, vn.y-len/TR/4);
if(a>=PI6 && a<PI63)
vn = area1;
else if(a>=PI6_3 && a<PI6_5)
vn = area2;
else if((a>=PI6_5 && a<=PI6_6) || (a<-PI6_5 && a>-PI6_6))
vn = area3;
else if(a<-PI6_3 && a>=-PI6_5)
vn = area4;
else if(a<=-PI6 && a>-PI63)
vn = area5;
else if(a>-PI6 && a<PI6)
vn = area6;
vec4 color = texture2DRect(colorTex0, vn);
gl_FragColor = color;
}