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#pragma comment(linker, "/SUBSYSTEM:WINDOWS /ENTRY:mainCRTStartup")
#include <GL/freeglut/freeglut.h>
#include <stdio.h>
#include <string>
#include "lodepng.h"
using namespace std;
#define WIDTH 640
#define HEIGHT 480
bool flag = false;
GLuint Tex[4];
int Current=-1;
string str="";
void Draw()
{
glEnable(GL_ALPHA_TEST);//アルファテスト開始
glBegin(GL_POLYGON);
glTexCoord2f(0.f, 0.f); glVertex3f(-0.5f,-0.5f,5.0f);
glTexCoord2f(1.f, 0.f); glVertex3f(0.5f,-0.5f,5.0f);
glTexCoord2f(1.f, 1.f); glVertex3f(0.5f,0.5f,-5.0f);
glTexCoord2f(0.f, 1.f); glVertex3f(-0.5f,0.5f,-5.0f);
glEnd();
glDisable(GL_ALPHA_TEST);//アルファテスト終了
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glViewport(0, 0, WIDTH, HEIGHT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//視野角,アスペクト比(ウィンドウの幅/高さ),描画する範囲(最も近い距離,最も遠い距離)
gluPerspective(30.0, (double)WIDTH / (double)HEIGHT, 1.0, 200.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
//視点の設定
gluLookAt(0.0,0.0,-5.0, //カメラの座標
0.0,0.0,0.0, // 注視点の座標
0.0,-1.0,0.0); // 画面の上方向を指すベクトル
glBindTexture(GL_TEXTURE_2D, Tex[Current]);
glEnable(GL_TEXTURE_2D);//テクスチャ有効
Draw();
glDisable(GL_TEXTURE_2D);//テクスチャ無効
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==4)Current=0;
str="ミップマップ";
if(Current==0)str+=":0 GL_NEAREST_MIPMAP_NEAREST";
if(Current==1)str+=":1 GL_LINEAR_MIPMAP_NEAREST ";
if(Current==2)str+=":2 GL_NEAREST_MIPMAP_LINEAR ";
if(Current==3)str+=":3 GL_LINEAR_MIPMAP_LINEAR ";
glutSetWindowTitle(str.c_str());
glutPostRedisplay();
}
}
void idle(void)
{
glutPostRedisplay();
}
void Init(){
glClearColor(0.0, 0.0, 0.0, 1.0);
glOrtho(0, WIDTH, HEIGHT, 0, -1, 1);
glEnable(GL_DEPTH);
LodePNG_Decoder decoder;
LodePNG_Decoder_init(&decoder);
unsigned char* buffer;
unsigned char* image;
size_t buffersize, imagesize;
//ロード
LodePNG_loadFile(&buffer, &buffersize, "maptip.png");
//デコード
LodePNG_decode(&decoder, &image, &imagesize, buffer,
buffersize);
//幅,高さ
int width = decoder.infoPng.width; int height = decoder.infoPng.height;
//ミップマップのフィルタ
GLenum Filter[4]={
GL_NEAREST_MIPMAP_NEAREST,
GL_LINEAR_MIPMAP_NEAREST,
GL_NEAREST_MIPMAP_LINEAR,
GL_LINEAR_MIPMAP_LINEAR};
glGenTextures(4,Tex);
glEnable( GL_TEXTURE_2D );
for(int i=0;i<4;i++)
{
//ミップマップ作成
glBindTexture( GL_TEXTURE_2D, Tex[i] );
gluBuild2DMipmaps(GL_TEXTURE_2D,GL_RGBA,width,height,GL_RGBA,GL_UNSIGNED_BYTE,image);
//拡大・縮小フィルタ
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,Filter[i]);
}
glDisable( GL_TEXTURE_2D );
key(' ',0,0);
}
int main(int argc, char *argv[])
{
glutInitWindowPosition(100, 100);
glutInitWindowSize(WIDTH, HEIGHT);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
glutCreateWindow("ミップマップ");
glutDisplayFunc(display);
glutKeyboardFunc(key);
glutIdleFunc(idle);
Init();
glutMainLoop();
return 0;
}
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