diff options
Diffstat (limited to 'progs/trivial/tri-fbo.c')
-rw-r--r-- | progs/trivial/tri-fbo.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/progs/trivial/tri-fbo.c b/progs/trivial/tri-fbo.c new file mode 100644 index 0000000..82d70c4 --- /dev/null +++ b/progs/trivial/tri-fbo.c @@ -0,0 +1,200 @@ + +#include <assert.h> +#include <stdio.h> +#include <stdlib.h> +#include <math.h> +#include <string.h> + +#define GL_GLEXT_PROTOTYPES +#include <GL/glut.h> + + + +static int Width = 400, Height = 400; +static GLuint MyFB, MyRB; + + +#define CheckError() assert(glGetError() == 0) + +GLenum doubleBuffer; + +static void Init(void) +{ + fprintf(stderr, "GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER)); + fprintf(stderr, "GL_VERSION = %s\n", (char *) glGetString(GL_VERSION)); + fprintf(stderr, "GL_VENDOR = %s\n", (char *) glGetString(GL_VENDOR)); + + + if (!glutExtensionSupported("GL_EXT_framebuffer_object")) { + printf("GL_EXT_framebuffer_object not found!\n"); + exit(0); + } + + + glGenFramebuffersEXT(1, &MyFB); + glGenRenderbuffersEXT(1, &MyRB); + + { + glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB); + + glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, MyRB); + + glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT1_EXT, + GL_RENDERBUFFER_EXT, MyRB); + + glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGB, Width, Height); + + glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); + } + + glClearColor(0.0, 0.0, 1.0, 0.0); +} + + + +static void +Reshape( int width, int height ) +{ + glViewport( 0, 0, width, height ); + glMatrixMode( GL_PROJECTION ); + glLoadIdentity(); + glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0); + glMatrixMode( GL_MODELVIEW ); + + Width = width; + Height = height; + glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGB, Width, Height); +} + + +static void Key(unsigned char key, int x, int y) +{ + + switch (key) { + case 27: + exit(1); + default: + return; + } + + glutPostRedisplay(); +} + + + +static void Draw( void ) +{ + + /* draw to user framebuffer */ + glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB); + glDrawBuffer(GL_COLOR_ATTACHMENT1_EXT); + glReadBuffer(GL_COLOR_ATTACHMENT1_EXT); + + glClearColor(0.5, 0.5, 1.0, 0.0); + glClear(GL_COLOR_BUFFER_BIT); + CheckError(); + + glBegin(GL_TRIANGLES); + glColor3f(0,0,.7); + glVertex3f( 0.9, -0.9, -30.0); + glColor3f(.8,0,0); + glVertex3f( 0.9, 0.9, -30.0); + glColor3f(0,.9,0); + glVertex3f(-0.9, 0.0, -30.0); + glEnd(); + + + { + GLubyte *buffer = malloc(Width * Height * 4); + + /* read from user framebuffer */ + glReadPixels(0, 0, Width-60, Height-60, GL_RGBA, GL_UNSIGNED_BYTE, buffer); + CheckError(); + + /* draw to window */ + glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); + /* Try to clear the window, but will overwrite: + */ + glClearColor(0.8, 0.8, 0, 0.0); + glClear(GL_COLOR_BUFFER_BIT); + + glWindowPos2iARB(30, 30); + glDrawPixels(Width-60, Height-60, GL_RGBA, GL_UNSIGNED_BYTE, buffer); + + + free(buffer); + } + + /* Bind normal framebuffer */ + glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); + + if (1) { + glBegin(GL_TRIANGLES); + glColor3f(0,.7,0); + glVertex3f( 0.5, -0.5, -30.0); + glColor3f(0,0,.8); + glVertex3f( 0.5, 0.5, -30.0); + glColor3f(.9,0,0); + glVertex3f(-0.5, 0.0, -30.0); + glEnd(); + } + + if (doubleBuffer) + glutSwapBuffers(); + else + glFinish(); + + CheckError(); +} + + +static GLenum Args(int argc, char **argv) +{ + GLint i; + + doubleBuffer = GL_FALSE; + + for (i = 1; i < argc; i++) { + if (strcmp(argv[i], "-sb") == 0) { + doubleBuffer = GL_FALSE; + } else if (strcmp(argv[i], "-db") == 0) { + doubleBuffer = GL_TRUE; + } else { + fprintf(stderr, "%s (Bad option).\n", argv[i]); + return GL_FALSE; + } + } + return GL_TRUE; +} + + + +int +main( int argc, char *argv[] ) +{ + GLenum type; + + glutInit(&argc, argv); + + if (Args(argc, argv) == GL_FALSE) { + exit(1); + } + + glutInitWindowPosition(100, 0); glutInitWindowSize( Width, Height ); + + type = GLUT_RGB; + type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE; + glutInitDisplayMode(type); + + if (glutCreateWindow(argv[0]) == GL_FALSE) { + exit(1); + } + + Init(); + + glutReshapeFunc(Reshape); + glutKeyboardFunc(Key); + glutDisplayFunc(Draw); + glutMainLoop(); + return 0; +} |