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