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#pragma comment(linker, "/SUBSYSTEM:WINDOWS /ENTRY:mainCRTStartup")
#pragma comment(lib, "glew32.lib")
#include <string>
#include <gl/glew.h>
#include <GL/freeglut/freeglut.h>
using namespace std;
#define WIDTH 640
#define HEIGHT 480
int Current=-1;
string str="";
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glViewport(0, 0, WIDTH, HEIGHT);
gluPerspective(30.0, double(WIDTH)/HEIGHT, 0.1, 200);
gluLookAt(0.0, 1.5, 3.0, 0.0 ,0.0 ,0.0, 0.0,1.0, 0.0);
glDisable(GL_DEPTH_TEST);//デプステストの無効化
glEnable(GL_BLEND);//ブレンドの有効化
//奥の物から描画
glTranslatef(0.0f,0.0f,-1.0f);
glColor4f(0.0f, 0.0f, 1.0f, 0.5f);//青
glRectf(-0.5,0.5,0.5,-0.5);
glTranslatef(0.0f,0.0f,1.0f);
glColor4f(1.f, 0.f, 0.f, 0.7f);//赤
glRectf(-0.5,0.5,0.5,-0.5);
glDisable(GL_BLEND);
glEnable(GL_DEPTH_TEST);
glutSwapBuffers();
}
void key(unsigned char key , int x , int y) {
if(key == ' '){//スペースキーで切り替え
Current++;
if(Current==6)Current=0;
str="アルファブレンディング";
if(Current==0){str+=":0 透明度無し描画";glBlendFunc(GL_ONE, GL_ZERO);}
if(Current==1){str+=":1 半透明合成";glBlendFunc(GL_SRC_ALPHA,
GL_ONE_MINUS_SRC_ALPHA);}
if(Current==2){str+=":2 加算合成";glBlendFunc(GL_SRC_ALPHA, GL_ONE);}
if(Current==3){str+=":3 減算合成";
glBlendEquationEXT(GL_FUNC_REVERSE_SUBTRACT_EXT);
glBlendFunc(GL_SRC_ALPHA, GL_ONE);}
if(Current==4){str+=":4 乗算合成";
glBlendEquationEXT(GL_FUNC_ADD_EXT);//glBlendEquationEXTを戻す
glBlendFunc(GL_ZERO, GL_SRC_COLOR);}
if(Current==5){str+=":5 反転合成";glBlendFunc(GL_ONE_MINUS_DST_COLOR,
GL_ZERO);}
glutSetWindowTitle(str.c_str());
glutPostRedisplay();
}
}
void idle(void)
{
glutPostRedisplay();
}
void Init(){
glewInit();
glClearColor(0.5f, 0.5f, 0.5f, 1.f);
glEnable(GL_DEPTH_TEST);
key(' ',0,0);
}
int main(int argc, char *argv[])
{
glutInitWindowPosition(100, 100);
glutInitWindowSize(WIDTH, HEIGHT);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
glutCreateWindow("アルファブレンディング");
glutDisplayFunc(display);
glutKeyboardFunc(key);
glutIdleFunc(idle);
Init();
glutMainLoop();
return 0;
}
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