opengl使用FBO离屏渲染图片

#include

#include

#include

#include

#pragma comment(lib, "glew32.lib")

GLuint imageFBO;

GLuint imageID;

GLuint depthTextureID;

void SetFrameBufferObject(int fbowidth, int fboheight)

{

// 创建FBO对象

glGenFramebuffersEXT(1, &imageFBO);

// 启用FBO

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, imageFBO);

// 创建纹理

glGenTextures(1, &imageID);

// 启用纹理

glBindTexture(GL_TEXTURE_2D, imageID);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, fbowidth, fboheight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, imageID, 0);

//

glGenRenderbuffersEXT(1, &depthTextureID);

glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, depthTextureID);

glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT,GL_DEPTH_COMPONENT, fbowidth, fboheight);

glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT,GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, depthTextureID);

GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);

if(status != GL_FRAMEBUFFER_COMPLETE_EXT)

printf( "FBO Initialization Failed.");

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

}

int IMAGE_WIDTH = 250;

int IMAGE_HEIGHT = 250;

void GenImage()

{

glPushMatrix();

glViewport(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

glMatrixMode(GL_MODELVIEW);

glShadeModel(GL_SMOOTH);

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, imageFBO);

glDrawBuffer(GL_COLOR_ATTACHMENT0_EXT);

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glBegin(GL_POLYGON);

glColor3f(1.0,0.0,0.0); glVertex3f(-1.0, -1.0, 0.0);

glColor3f(0.0,1.0,0.0); glVertex3f(-1.0, 1.0, 0.0);

glColor3f(0.0,0.0,1.0); glVertex3f(1.0, 1.0, 0.0);

glColor3f(1.0,0.0,0.0); glVertex3f(1.0, -1.0, 0.0);

glEnd();

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

glPopMatrix();

}

static GLuint texName;

void display(void)

{

// 离屏渲染纹理

GenImage();

glViewport(0,0,250,250);

glClear(GL_COLOR_BUFFER_BIT);

glEnable(GL_TEXTURE_2D);

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

//切换屏幕

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT,0);

// 启用离屏渲染的纹理影像

glBindTexture(GL_TEXTURE_2D,imageID);

// 创建Mipmap(多重细节层)

glGenerateMipmapEXT(GL_TEXTURE_2D);

// 绘制纹理影像

glBegin(GL_QUADS);

glTexCoord2f(1.0, 0.0); glVertex3f(-1.0, -1.0, 0.0);

glTexCoord2f(0.0, 1.0); glVertex3f(-1.0, 1.0, 0.0);

glTexCoord2f(1.0, 1.0); glVertex3f(1.0, 1.0, 0.0);

glTexCoord2f(1.0, 0.0); glVertex3f(1.0, -1.0, 0.0);

glEnd();

glutSwapBuffers();

glDisable(GL_TEXTURE_2D);

}

void reshape(int w, int h)

{

glViewport(0, 0, (GLsizei) w, (GLsizei) h);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

}

void keyboard (unsigned char key, int x, int y)

{

switch (key) {

case 27:

exit(0);

break;

default:

break;

}

}

int main(int argc, char** argv)

{

glutInit(&argc, argv);

glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);

glutInitWindowSize(250, 250);

glutInitWindowPosition(100, 100);

glutCreateWindow(argv[0]);

glewInit();

glutDisplayFunc(display);

glutReshapeFunc(reshape);

glutKeyboardFunc(keyboard);

// 设置创建虚拟屏幕

SetFrameBufferObject(IMAGE_WIDTH, IMAGE_HEIGHT);

glutMainLoop();

return 0;

}