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/**
* Test XOR emulation with blending.
*
*/
#define GL_GLEXT_PROTOTYPES
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>
#include "readtex.c"
#define IMAGE_FILE "../images/arch.rgb"
static int ImgWidth, ImgHeight;
static GLenum ImgFormat;
static GLubyte *Image = NULL;
static int Win;
static int Width = 600, Height = 600;
struct rect
{
int x0, y0, x1, y1;
};
static struct rect OldRect, NewRect;
static GLboolean ButtonDown = GL_FALSE;
static GLboolean LogicOp = 0*GL_TRUE;
static const GLfloat red[4] = {1.0, 0.2, 0.2, 1.0};
static const GLfloat green[4] = {0.2, 1.0, 0.2, 1.0};
static const GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};
static void
PrintString(const char *s)
{
while (*s) {
glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
s++;
}
}
static void
Draw(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glWindowPos2i((Width - ImgWidth) / 2, (Height - ImgHeight) / 2);
glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
/*
* Draw 2D XOR rects
*/
glColor3f(1, 1, 1);
glWindowPos2i(100, Height - 20);
PrintString("XOR LogicOp:");
glLogicOp(GL_XOR);
glEnable(GL_COLOR_LOGIC_OP);
glRecti(100, 30, 250, Height - 30);
glDisable(GL_COLOR_LOGIC_OP);
glWindowPos2i(Width/2 + 10, Height - 20);
PrintString("Invert Blending:");
glBlendFunc(GL_ONE, GL_ONE);
glBlendEquation(GL_FUNC_SUBTRACT);
glEnable(GL_BLEND);
glRecti(Width / 2, 30, Width / 2 + 150, Height - 30);
glDisable(GL_BLEND);
glutSwapBuffers();
}
static void
Reshape(int width, int height)
{
Width = width;
Height = height;
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, Width, 0, Height, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
static void
Key(unsigned char key, int x, int y)
{
(void) x;
(void) y;
switch (key) {
case 'b':
case 'B':
LogicOp = GL_FALSE;
break;
case 'l':
case 'L':
LogicOp = GL_TRUE;
break;
case 27:
glutDestroyWindow(Win);
exit(0);
break;
}
glutPostRedisplay();
}
static void
SpecialKey(int key, int x, int y)
{
(void) x;
(void) y;
switch (key) {
case GLUT_KEY_UP:
break;
case GLUT_KEY_DOWN:
break;
case GLUT_KEY_LEFT:
break;
case GLUT_KEY_RIGHT:
break;
}
glutPostRedisplay();
}
static void
MouseMotion(int x, int y)
{
if (ButtonDown) {
NewRect.x1 = x;
NewRect.y1 = y;
glutPostRedisplay();
}
}
static void
MouseButton(int button, int state, int x, int y)
{
if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
ButtonDown = GL_TRUE;
NewRect.x0 = NewRect.x1 = x;
NewRect.y0 = NewRect.y1 = y;
OldRect = NewRect;
}
else if (button == GLUT_LEFT_BUTTON && state == GLUT_UP) {
ButtonDown = GL_FALSE;
}
}
static void
Init(void)
{
/*
* Load image and scale if needed.
*/
Image = LoadRGBImage(IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat);
if (!Image) {
printf("Couldn't read %s\n", IMAGE_FILE);
exit(0);
}
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glPixelStorei(GL_PACK_ALIGNMENT, 1);
}
int
main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowSize(Width, Height);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
Win = glutCreateWindow(argv[0]);
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutSpecialFunc(SpecialKey);
glutMotionFunc(MouseMotion);
glutMouseFunc(MouseButton);
glutDisplayFunc(Draw);
Init();
glutPostRedisplay();
glutMainLoop();
return 0;
}
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