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-rw-r--r--progs/trivial/clear-fbo.c207
1 files changed, 207 insertions, 0 deletions
diff --git a/progs/trivial/clear-fbo.c b/progs/trivial/clear-fbo.c
new file mode 100644
index 0000000000..64b25430c6
--- /dev/null
+++ b/progs/trivial/clear-fbo.c
@@ -0,0 +1,207 @@
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <string.h>
+
+#include <GL/glew.h>
+#include <GL/glut.h>
+
+
+
+static int Width = 512, Height = 512;
+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);
+ }
+
+}
+
+
+
+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);
+
+
+ glViewport(0, 0, Width, Height);
+ CheckError();
+
+ glClearColor(0.5, 0.5, 1.0, 0.0);
+ glClear(GL_COLOR_BUFFER_BIT);
+ CheckError();
+
+ if (0) {
+ 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);
+ glViewport(0, 0, Width, Height);
+
+ /* 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);
+ glViewport(0, 0, Width, Height);
+
+ if (0) {
+ 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);
+ }
+
+ glewInit();
+
+ Init();
+
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutDisplayFunc(Draw);
+ glutMainLoop();
+ return 0;
+}