高效学习OpenGL之执行多个显示列表glListBase(),glCallLists()

#include <GL/glut.h>

002.#include <stdlib.h>

003.#include <string.h>

004. 

005.#define PT 1

006.#define STROKE 2

007.#define END 3

008. 

009.typedef struct charpoint {

010.GLfloat   x, y;

011.int    type;

012.} CP;

013. 

014.CP Adata[] = {

015.{ 0, 0, PT}, {0, 9, PT}, {1, 10, PT}, {4, 10, PT},

016.{5, 9, PT}, {5, 0, STROKE}, {0, 5, PT}, {5, 5, END}

017.};

018. 

019.CP Edata[] = {

020.{5, 0, PT}, {0, 0, PT}, {0, 10, PT}, {5, 10, STROKE},

021.{0, 5, PT}, {4, 5, END}

022.};

023. 

024.CP Pdata[] = {

025.{0, 0, PT}, {0, 10, PT},  {4, 10, PT}, {5, 9, PT}, {5, 6, PT},

026.{4, 5, PT}, {0, 5, END}

027.};

028. 

029.CP Rdata[] = {

030.{0, 0, PT}, {0, 10, PT},  {4, 10, PT}, {5, 9, PT}, {5, 6, PT},

031.{4, 5, PT}, {0, 5, STROKE}, {3, 5, PT}, {5, 0, END}

032.};

033. 

034.CP Sdata[] = {

035.{0, 1, PT}, {1, 0, PT}, {4, 0, PT}, {5, 1, PT}, {5, 4, PT},

036.{4, 5, PT}, {1, 5, PT}, {0, 6, PT}, {0, 9, PT}, {1, 10, PT},

037.{4, 10, PT}, {5, 9, END}

038.};

039. 

040./*  drawLetter() interprets the instructions from the array

041.*  for that letter and renders the letter with line segments.

042.*/

043.static void drawLetter(CP *l)

044.{

045.glBegin(GL_LINE_STRIP);

046.while (1) {

047.switch (l->type) {

048.case PT:

049.glVertex2fv(&l->x);

050.break;

051.case STROKE:

052.glVertex2fv(&l->x);

053.glEnd();

054.glBegin(GL_LINE_STRIP);

055.break;

056.case END:

057.glVertex2fv(&l->x);

058.glEnd();

059.glTranslatef(8.0, 0.0, 0.0);

060.return;

061.}

062.l++;

063.}

064.}

065. 

066./*  Create a display list for each of 6 characters  */

067.static void init (void)

068.{

069.GLuint base;

070. 

071.glShadeModel (GL_FLAT);

072. 

073.base = glGenLists (128);

074.glListBase(base);//指定一个偏移量，它将与glCallListserv()函数中的

075.//显示列表索引相加，以获取最终的显示列表索引

076.glNewList(base+'A', GL_COMPILE); drawLetter(Adata); glEndList();

077.glNewList(base+'E', GL_COMPILE); drawLetter(Edata); glEndList();

078.glNewList(base+'P', GL_COMPILE); drawLetter(Pdata); glEndList();

079.glNewList(base+'R', GL_COMPILE); drawLetter(Rdata); glEndList();

080.glNewList(base+'S', GL_COMPILE); drawLetter(Sdata); glEndList();

081.glNewList(base+' ', GL_COMPILE); glTranslatef(8.0, 0.0, 0.0); glEndList();

082.}

083. 

084.char *test1 = "A SPARE SERAPE APPEARS AS";

085.char *test2 = "APES PREPARE RARE PEPPERS";

086. 

087.static void printStrokedString(char *s)

088.{

089.GLsizei len = strlen(s);

090.glCallLists(len, GL_BYTE, (GLbyte *)s);

091.//执行len个显示列表，被执行的显示列表的索引是通过把当前显示列表基址表示的偏移值（由glListBase()指定）

092.//与s指向的数组中的有符号整型值相加得到的

093.}

094. 

095.void display(void)

096.{

097.glClear(GL_COLOR_BUFFER_BIT);

098.glColor3f(1.0, 1.0, 1.0);

099.glPushMatrix();

100.glScalef(2.0, 2.0, 2.0);

101.glTranslatef(10.0, 30.0, 0.0);

102.printStrokedString(test1);

103.glPopMatrix();

104.glPushMatrix();

105.glScalef(2.0, 2.0, 2.0);

106.glTranslatef(10.0, 13.0, 0.0);

107.printStrokedString(test2);

108.glPopMatrix();

109.glFlush();

110.}

111. 

112.void reshape(int w, int h)

113.{

114.glViewport(0, 0, (GLsizei) w, (GLsizei) h);

115.glMatrixMode (GL_PROJECTION);

116.glLoadIdentity ();

117.gluOrtho2D (0.0, (GLdouble) w, 0.0, (GLdouble) h);

118.}

119. 

120.void keyboard(unsigned char key, int x, int y)

121.{

122.switch (key) {

123.case ' ':

124.glutPostRedisplay();

125.break;

126.case 27:

127.exit(0);

128.}

129.}

130. 

131./*  Main Loop

132.*  Open window with initial window size, title bar,

133.*  RGBA display mode, and handle input events.

134.*/

135.int main(int argc, char** argv)

136.{

137.glutInit(&argc, argv);

138.glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);

139.glutInitWindowSize (440, 120);

140.glutCreateWindow ("stroke");

141.init ();

142.glutReshapeFunc(reshape);

143.glutKeyboardFunc(keyboard);

144.glutDisplayFunc(display);

145.glutMainLoop();

146.return 0;

147.}