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-rw-r--r--progs/demos/dissolve.c158
1 files changed, 158 insertions, 0 deletions
diff --git a/progs/demos/dissolve.c b/progs/demos/dissolve.c
new file mode 100644
index 00000000000..f1589a4e413
--- /dev/null
+++ b/progs/demos/dissolve.c
@@ -0,0 +1,158 @@
+/**
+ * Dissolve between two images using randomized stencil buffer
+ * and varying stencil ref.
+ *
+ * Brian Paul
+ * 29 Jan 2010
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glut.h>
+#include "readtex.h"
+
+#define FILE1 "../images/bw.rgb"
+#define FILE2 "../images/arch.rgb"
+
+
+static int Win;
+static int WinWidth = 400, WinHeight = 400;
+static GLboolean Anim = GL_TRUE;
+
+static int ImgWidth[2], ImgHeight[2];
+static GLenum ImgFormat[2];
+static GLubyte *Image[2];
+static GLfloat ScaleX[2], ScaleY[2];
+
+static GLubyte StencilRef = 0;
+
+
+static void
+Idle(void)
+{
+ StencilRef = (GLint) (glutGet(GLUT_ELAPSED_TIME) / 10);
+ glutPostRedisplay();
+}
+
+
+static void
+RandomizeStencilBuffer(void)
+{
+ GLubyte *b = malloc(WinWidth * WinHeight);
+ int i;
+ for (i = 0; i < WinWidth * WinHeight; i++) {
+ b[i] = rand() & 0xff;
+ }
+
+ glStencilFunc(GL_ALWAYS, 0, ~0);
+ glPixelZoom(1.0, 1.0);
+ glDrawPixels(WinWidth, WinHeight, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, b);
+
+ free(b);
+}
+
+
+
+static void
+Draw(void)
+{
+ glClear(GL_COLOR_BUFFER_BIT);
+
+ glPixelZoom(ScaleX[0], ScaleY[0]);
+ glStencilFunc(GL_LESS, StencilRef, ~0);
+ glDrawPixels(ImgWidth[0], ImgHeight[0], ImgFormat[0], GL_UNSIGNED_BYTE, Image[0]);
+
+ glPixelZoom(ScaleX[1], ScaleY[1]);
+ glStencilFunc(GL_GEQUAL, StencilRef, ~0);
+ glDrawPixels(ImgWidth[1], ImgHeight[1], ImgFormat[1], GL_UNSIGNED_BYTE, Image[1]);
+
+ glutSwapBuffers();
+}
+
+
+static void
+Reshape(int width, int height)
+{
+ WinWidth = width;
+ WinHeight = height;
+ glViewport(0, 0, width, height);
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+ glTranslatef(0.0, 0.0, -15.0);
+
+ RandomizeStencilBuffer();
+
+ ScaleX[0] = (float) width / ImgWidth[0];
+ ScaleY[0] = (float) height / ImgHeight[0];
+
+ ScaleX[1] = (float) width / ImgWidth[1];
+ ScaleY[1] = (float) height / ImgHeight[1];
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+ (void) x;
+ (void) y;
+ switch (key) {
+ case 'a':
+ Anim = !Anim;
+ if (Anim)
+ glutIdleFunc(Idle);
+ else
+ glutIdleFunc(NULL);
+ break;
+ case 27:
+ glutDestroyWindow(Win);
+ exit(0);
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+
+static void
+Init(void)
+{
+ Image[0] = LoadRGBImage(FILE1, &ImgWidth[0], &ImgHeight[0], &ImgFormat[0]);
+ if (!Image[0]) {
+ printf("Couldn't read %s\n", FILE1);
+ exit(0);
+ }
+
+ Image[1] = LoadRGBImage(FILE2, &ImgWidth[1], &ImgHeight[1], &ImgFormat[1]);
+ if (!Image[1]) {
+ printf("Couldn't read %s\n", FILE1);
+ exit(0);
+ }
+
+ glEnable(GL_STENCIL_TEST);
+ glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
+
+ glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+}
+
+
+int
+main(int argc, char *argv[])
+{
+ glutInit(&argc, argv);
+ glutInitWindowSize(WinWidth, WinHeight);
+ glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_STENCIL);
+ Win = glutCreateWindow(argv[0]);
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutDisplayFunc(Draw);
+ if (Anim)
+ glutIdleFunc(Idle);
+ Init();
+ glutMainLoop();
+ return 0;
+}