使用OpenGL渲染QImage [英] Render QImage with OpenGL

问题描述

与我的其他问题相关，我认为更核心的问题是的，你如何使用OpenGL渲染一个 QImage ？

Related to my other question, I think the more central question would be, how you render a QImage with OpenGL?

我认为代码看起来像这样，我不确定我还需要什么，除了 convertToGLFormat（img）。

I think the code has to look something like this, but I'm not sure what else I need, besides maybe convertToGLFormat(img).

glEnable(GL_TEXTURE_2D);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glGenTextures(1, &offscreenBufferTexture);
glBindTexture(GL_TEXTURE_2D, offscreenBufferTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imgGL.width(),
         imgGL.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
         imgGL.bits());

glBegin(GL_QUADS);
  glTexCoord2d(0,0); glVertex2d(0, 0);
  glTexCoord2d(1,0); glVertex2d(windowSize.width(), 0);
  glTexCoord2d(1,1); glVertex2d(windowSize.width(), windowSize.height());
  glTexCoord2d(0,1); glVertex2d(0, windowSize.height());
glEnd();
glDisable(GL_TEXTURE_2D);

此外，我认为你可以使用 glDrawPixels code>（虽然你不应该），像

Also, I thought quick and dirty you could use glDrawPixels() (although you shouldn't), like

glDrawPixels(imgGL.width(), imgGL.height(), GL_RGBA,
         GL_UNSIGNED_BYTE, imgGL.bits());

但是无论哪种方式，我看不到图像，只是一个白色方形的大小。我缺少这里的东西。

But either way I can't see the image, just a white square with the size of it. I'm missing something here.

推荐答案

我设法绘制一个 QImage 使用OpenGL从图片源，但不是 SoOffscreenRenderer ，如在这里。

I managed to draw a QImage with OpenGL from a picture source, but not from the SoOffscreenRenderer as described here.

void init(){
    loadTexture2("kitten.png", backgroundimage);
}

QImage loadTexture2(char *filename, GLuint &textureID){
    glEnable(GL_TEXTURE_2D); // Enable texturing

    glGenTextures(1, &textureID); // Obtain an id for the texture
    glBindTexture(GL_TEXTURE_2D, textureID); // Set as the current texture

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

    QImage im(filename);
    QImage tex = QGLWidget::convertToGLFormat(im);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tex.width(), tex.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, tex.bits());

    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);

    glDisable(GL_TEXTURE_2D);

    return tex;
}

void renderSceneGL2(){
    glClearColor(0.4f, 0.1f, 0.1f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, backgroundimage);

    glBegin(GL_QUADS);
        glTexCoord2f(0,0); glVertex3f(-1, -1, -1);
        glTexCoord2f(1,0); glVertex3f(1, -1, -1);
        glTexCoord2f(1,1); glVertex3f(1, 1, -1);
        glTexCoord2f(0,1); glVertex3f(-1, 1, -1);

    glEnd();

    glDisable(GL_TEXTURE_2D);
}

也 QGLWidget :: convertToGLFormat 不定期抛出随机访问冲突错误。

Also QGLWidget::convertToGLFormat throws random Access violation errors from time to time.

这篇关于使用OpenGL渲染QImage的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！