本文介绍了OpenGl纹理.......... ppm背景的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我使用ppm加载程序将图像设置为背景，但有一个问题
在这里的颜色是我使用的代码和图像。
p>
这里是代码.....
texture.h
#ifndef TEXTURE_H
#define TEXTURE_H
struct Image
{
unsigned char * pixels;
int width;
int height;
int numChannels;
};
class Texture
{
public：
Texture（）;
void Prepare（int texN）;
void ReadPPMImage（char * fn）;
GLuint texName;
图像图像;
};
#endif
texture.cpp
#include< fstream>
#include< glut.h>
#pragma warning（disable：4996）
#includeTexture.h
Texture :: Texture（）
{
}
void Texture :: Prepare（int texN）
{
texName = texN;
glPixelStorei（GL_UNPACK_ALIGNMENT，1）;
glBindTexture（GL_TEXTURE_2D，texName）;
glTexParameteri（GL_TEXTURE_2D，GL_TEXTURE_WRAP_S，GL_REPEAT）;
glTexParameteri（GL_TEXTURE_2D，GL_TEXTURE_WRAP_T，GL_REPEAT）;
glTexParameteri（GL_TEXTURE_2D，GL_TEXTURE_MAG_FILTER，GL_NEAREST）;
glTexParameteri（GL_TEXTURE_2D，GL_TEXTURE_MIN_FILTER，GL_NEAREST）;
glTexImage2D（GL_TEXTURE_2D，0，GL_RGB，image.width，
image.height，0，GL_RGB，GL_UNSIGNED_BYTE，
image.pixels）;
}
void Texture :: ReadPPMImage（char * fn）
{
int tmpint;
char str [100];
FILE * inFile = fopen（fn，rb）;
if（inFile == NULL）
{
printf（无法打开输入文件％s。Exiting.\\\
，fn）;
exit（1）;
}
fscanf（inFile，P％d \\\
，& tmpint）;
if（tmpint！= 6）
{
printf（Input file is not ppm。Exiting.\\\
）;
exit（1）;
}
//跳过标题中嵌入的注释
fgets（str，100，inFile）;
while（str [0] =='＃'）
fgets（str，100，inFile）;
//读取图片尺寸
sscanf（str，％d％d，& image.width，& image.height）;
fgets（str，100，inFile）;
sscanf（str，％d，& tmpint）;
if（tmpint！= 255）
printf（Warning：maxvalue is not 255 in ppm file\\\
）;
image.numChannels = 3;
image.pixels =（unsigned char *）malloc（image.numChannels * image.width * image.height * sizeof（unsigned char））;
if（image.pixels == NULL）
{
printf（无法分配大小为％dx％d的图片。退出\\\
，image.width ，image.height）;
exit（1）;
}
else
printf（读取图像％s的大小％dx％d \\\
，fn，image.width，image.height）;
fread（image.pixels，sizeof（unsigned char），image.numChannels * image.width * image.height，inFile）;
fclose（inFile）;
}
Main.cpp
#include< glut.h>
#includeTexture.h
#pragma warning（disable：4996）
const float fMinX = -5.0，fMinY = -5.0，fNearZ = 1.0，
fMaxX = 5.0，fMaxY = 5.0，fFarZ = 10.0;
纹理ImageOne;
void Init（）
{
glClearColor（0.0，0.0，0.0，0.0）;
glEnable（GL_DEPTH_TEST）;
glGenTextures（1，& ImageOne.texName）;
ImageOne.ReadPPMImage（wood_1.ppm）;
ImageOne.Prepare（1）;
}
void Reshape（int width，int height）
{
glViewport（0，0，width，height）;
glMatrixMode（GL_PROJECTION）;
glLoadIdentity（）;
glOrtho（fMinX，fMaxX，fMinY，fMaxY，fNearZ，fFarZ）;
glMatrixMode（GL_MODELVIEW）;
glLoadIdentity（）;
}
void Display（）
{
glClear（GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT）;
glEnable（GL_TEXTURE_2D）;
glTexEnvf（GL_TEXTURE_ENV，GL_TEXTURE_ENV_MODE，GL_BLEND）;
glBindTexture（GL_TEXTURE_2D，ImageOne.texName）;
glBegin（GL_QUADS）;
glTexCoord2f（0,1）;
glVertex3f（-5.5,5，-6）;
glTexCoord2f（0,0）;
glVertex3f（-5.5，-5，-6）;
glTexCoord2f（1,0）;
glVertex3f（5，-5，-6）;
glTexCoord2f（1,1）;
glVertex3f（5,5，-6）;
glEnd（）;
glDisable（GL_TEXTURE_2D）;
glutSwapBuffers（）;
glFlush（）;
}
void main（int argc，char ** argv）
{
//初始化GLUT并创建窗口
glutInit（& argc， argv）;
glutInitDisplayMode（GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH）;
glutInitWindowPosition（100,100）;
glutInitWindowSize（500,500）;
glutCreateWindow（OpenGL - Rotating Cubes）;
Init（）;
//注册回调
glutDisplayFunc（Display）;
glutReshapeFunc（Reshape）;
glutIdleFunc（Display）; //用于动画
//输入GLUT事件处理周期
glutMainLoop（）;
}
解决方案
p>
？
它对你的用例没有意义（并完全显示颜色值的反转）。您可能需要 GL_REPLACE 或 GL_MODULATE 。
i am using a ppm loader to set image as a background , but there is a problemin colors here is the code and the image that i am use .
here is the code .....
texture.h
#ifndef TEXTURE_H
#define TEXTURE_H
struct Image
{
unsigned char* pixels;
int width;
int height;
int numChannels;
};
class Texture
{
public:
Texture ();
void Prepare (int texN);
void ReadPPMImage (char *fn);
GLuint texName;
Image image;
};
#endif
texture.cpp
#include <fstream>
#include <glut.h>
#pragma warning (disable : 4996)
#include "Texture.h"
Texture::Texture ()
{
}
void Texture::Prepare (int texN)
{
texName = texN;
glPixelStorei (GL_UNPACK_ALIGNMENT, 1);
glBindTexture (GL_TEXTURE_2D, texName);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.width,
image.height, 0, GL_RGB, GL_UNSIGNED_BYTE,
image.pixels);
}
void Texture::ReadPPMImage (char* fn)
{
int tmpint;
char str[100];
FILE* inFile = fopen (fn,"rb");
if (inFile == NULL)
{
printf ("Can't open input file %s. Exiting.\n",fn);
exit (1);
}
fscanf (inFile,"P%d\n", &tmpint);
if (tmpint != 6)
{
printf ("Input file is not ppm. Exiting.\n");
exit (1);
}
// skip comments embedded in header
fgets (str,100,inFile);
while (str[0]=='#')
fgets(str,100,inFile);
// read image dimensions
sscanf (str,"%d %d",&image.width, &image.height);
fgets (str,100,inFile);
sscanf (str,"%d",&tmpint);
if (tmpint != 255)
printf("Warning: maxvalue is not 255 in ppm file\n");
image.numChannels = 3;
image.pixels = (unsigned char*) malloc (image.numChannels * image.width * image.height * sizeof (unsigned char));
if (image.pixels == NULL)
{
printf ("Can't allocate image of size %dx%d. Exiting\n", image.width, image.height);
exit (1);
}
else
printf("Reading image %s of size %dx%d\n", fn, image.width, image.height);
fread (image.pixels, sizeof (unsigned char), image.numChannels * image.width * image.height, inFile);
fclose (inFile);
}
Main.cpp
#include <glut.h>
#include "Texture.h"
#pragma warning (disable : 4996)
const float fMinX = -5.0, fMinY = -5.0, fNearZ = 1.0,
fMaxX = 5.0 , fMaxY = 5.0 , fFarZ = 10.0;
Texture ImageOne ;
void Init ()
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glEnable (GL_DEPTH_TEST);
glGenTextures (1, &ImageOne.texName);
ImageOne.ReadPPMImage("wood_1.ppm");
ImageOne.Prepare(1) ;
}
void Reshape (int width, int height)
{
glViewport (0, 0, width, height);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrtho (fMinX, fMaxX, fMinY, fMaxY, fNearZ, fFarZ);
glMatrixMode (GL_MODELVIEW);
glLoadIdentity ();
}
void Display ()
{
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable (GL_TEXTURE_2D);
glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND);
glBindTexture (GL_TEXTURE_2D, ImageOne.texName);
glBegin(GL_QUADS);
glTexCoord2f(0,1);
glVertex3f(-5.5,5,-6);
glTexCoord2f(0,0);
glVertex3f(-5.5,-5,-6);
glTexCoord2f(1,0);
glVertex3f(5,-5,-6);
glTexCoord2f(1,1);
glVertex3f(5,5,-6);
glEnd();
glDisable(GL_TEXTURE_2D);
glutSwapBuffers ();
glFlush ();
}
void main (int argc, char **argv)
{
// init GLUT and create window
glutInit (&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowPosition(100,100);
glutInitWindowSize(500,500);
glutCreateWindow ("OpenGL - Rotating Cubes");
Init ();
// register callbacks
glutDisplayFunc (Display);
glutReshapeFunc (Reshape);
glutIdleFunc (Display); // used in animation
// enter GLUT event processing cycle
glutMainLoop();
}
解决方案
Why are you using
?
It does not make sense for your use case (and perfectly explays the "inversion" of the color values). You probably want GL_REPLACE or GL_MODULATE.
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