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发表于 2011-7-19 17:00:00
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Re:glConvolutionFilter2D
#include <windows.h>
#include <GL/glew.h>
#include <GL/glut.h>
#include <cstdio>
#include <cstdlib>
#include <iostream>
using namespace std;
GLubyte *pixels;
GLsizei width, height;
GLubyte * readImage( const char* filename, GLsizei* width, GLsizei *height )
{
int n;
GLubyte * pixels;
FILE * infile = fopen( filename, "rb" );
if ( !infile )
{
fprintf( stderr, "Unable to open file '%s'\n", filename );
return NULL;
}
fread( width, sizeof( GLsizei ), 1, infile );
cout<<"width is "<<width<<endl;
fread( height, sizeof( GLsizei ), 1, infile );
cout<<"height is "<<height<<endl;
n = 3 * (*width) * (*height);
pixels = (GLubyte *) malloc( n * sizeof( GLubyte ));
if ( !pixels )
{
fprintf( stderr, "Unable to malloc() bytes for pixels\n" );
return NULL;
}
fread( pixels, sizeof( GLubyte ), n, infile );
fclose( infile );
return pixels;
}
GLfloat horizontal[3][3] =
{
{ 0, -1, 0 },
{ 0, 1, 0 },
{ 0, 0, 0 }
};
GLfloat vertical[3][3] =
{
{ 0, 0, 0 },
{ -1, 1, 0 },
{ 0, 0, 0 }
};
GLfloat laplacian[3][3] = {
{ -0.125, -0.125, -0.125 },
{ -0.125, 1.0 , -0.125 },
{ -0.125, -0.125, -0.125 },
};
void init(void)
{
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glClearColor(0.0, 0.0, 0.0, 0.0);
printf("Using the horizontal filter\n");
glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_LUMINANCE,
3, 3, GL_LUMINANCE, GL_FLOAT, horizontal);
glEnable(GL_CONVOLUTION_2D);
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glRasterPos2i( 1, 1);
glDrawPixels(width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels);
glFlush();
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, w, 0, h, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
}
void keyboard(unsigned char key, int x, int y)
{
switch (key)
{
case 'h' :
printf("Using a horizontal filter\n");
glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_LUMINANCE, 3, 3,
GL_LUMINANCE, GL_FLOAT, horizontal);
break;
case 'v' :
printf("Using the vertical filter\n");
glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_LUMINANCE, 3, 3,
GL_LUMINANCE, GL_FLOAT, vertical);
break;
case 'l' :
printf("Using the laplacian filter\n");
glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_LUMINANCE, 3, 3,
GL_LUMINANCE, GL_FLOAT, laplacian);
break;
case 27:
exit(0);
}
glutPostRedisplay();
}
/* Main Loop
* Open window with initial window size, title bar,
* RGBA display mode, and handle input events.
*/
int main(int argc, char** argv)
{
pixels = readImage("leeds(1).bin", &width, &height);
cout<<"Width = "<<width <<" Height = "<<height<<endl;
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA);
glutInitWindowSize(width, height);
glutInitWindowPosition(100, 100);
glutCreateWindow("Demo of convolution");
//初始化OpenGL扩展。
glewInit();
init();
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutDisplayFunc(display);
glutMainLoop();
return 0;
}
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