采取截图使用OpenGL，并保存为PNG [英] Take screenshot with openGL and save it as png

问题描述

我试图把全屏幕截图，并保存为png。我发现了一个code <一个href=\"http://$c$c.google.com/p/fds-smv/source/browse/trunk/FDS/trunk/SMV_5/source/smokeview/renderfile.c?r=3037&spec=svn3037\"相对=nofollow>这里并修改它一下。对于我的截图使用OpenGL和戊二醛和在巴GD库对C的保存。所有我得到是一个黑色的PNG，我想不通为什么。我搜索在计算器并发现了一些岗位，但遗憾的是他们并没有帮助。其中之一是使用glReadBuffer（GL_FRONT）;而不是glReadBuffer（GL_BACK）;我trye​​d与他们两个，但没有成功。这里是我的code：

I'm trying to take a screenshot of full screen and save it as a png. I found a code here and modified it a bit. For the screenshot I use openGL and Glut and for the saving in png the gd library for c. All I'm getting is a black png and I can't figure out why. I searched in stackoverflow and found some posts, but unfortunately they didn't help. One of them was to use glReadBuffer( GL_FRONT); instead of glReadBuffer(GL_BACK); I tryed with both of them with no success. Here is my code:

int SVimage2file(char *filename){
    int width = glutGet(GLUT_SCREEN_WIDTH);
    int height = glutGet( GLUT_SCREEN_HEIGHT);
    FILE *png;
    GLubyte *OpenGLimage, *p;
    gdImagePtr image;
    unsigned int r, g, b;
    int i,j,rgb;

    png = fopen(filename, "wb");

    if (png == NULL) {
        printf("*** warning:  unable to write to %s\n",filename);
        return 1;
    }

    OpenGLimage = (GLubyte *) malloc(width * height * sizeof(GLubyte) * 3);
    if(OpenGLimage == NULL){
        printf("error allocating image:%s\n",filename);
        exit(1);
    }

    printf("Saving to: %s .\n",filename);
    glPixelStorei(GL_PACK_ALIGNMENT, 1);
    glReadBuffer( GL_FRONT);
    glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, OpenGLimage);
    p = OpenGLimage;
    image = gdImageCreateTrueColor(width,height);

    for (i = height-1 ; i>=0; i--) {
        for(j=0;j<width;j++){
                r=*p++; g=*p++; b=*p++;
                rgb = (r<<16)|(g<<8)|b;
                //printf("the rgb color %d\n", rgb );
                gdImageSetPixel(image,j,i,rgb);
        }
    }

    gdImagePng(image,png);
    fclose(png);
    gdImageDestroy(image);
}

它是什么，我失踪？

What is it that I'm missing?

推荐答案

您可以使用魔鬼的图像库并采取screeshot有：

You could use the devil image library and take a screeshot with:

void takeScreenshot(const char* screenshotFile)
{
    ILuint imageID = ilGenImage();
    ilBindImage(imageID);
    ilutGLScreen();
    ilEnable(IL_FILE_OVERWRITE);
    ilSaveImage(screenshotFile);
    ilDeleteImage(imageID);
    printf("Screenshot saved to: %s\n", screenshotFile);
}

takeScreenshot("screenshot.png");

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