OpenGL 学习笔记3_2(绘制线相关)

蓝宝书 第三章

画线 Line

1）两点定一条实线

glBegin(GL_LINES);

glVertex3f(……);//点a

glVertex3f(……);//点b

glVertex3f(……);//点c

glVertex3f(……);//点d

glEnd();

绘制线段ab、cd

相关代码见例3.4

2）绘制连续线段，连接密集的点成曲线

glBegin(GL_LINE_STRIP);

glVertex3f(……);//点a

glVertex3f(……);//点b

glVertex3f(……);//点c

glVertex3f(……);//点d

glEnd();

绘制线段ab、bc、cd

相关代码见例3.5

3）设置线宽度

voidglLineWidth(GLfloatwidth);设置线宽度

GLfloat sizes[2]; // 存放线宽度的范围

GLfloat step; // 存放每次改变线宽度的最小增量

glGetFloatv(GL_LINE_WIDTH_RANGE,sizes);//获取线宽范围

glGetFloatv(GL_LINE_WIDTH_GRANULARITY,&step);//获取最小增量

相关代码见例3.6

4）绘制虚线，自定义虚线模板

glEnable(GL_LINE_STIPPLE);//启用模板功能

void glLineStipple(GLintfactor, GLushort pattern);//设置影响因子及模板格式

factor代表每位二进制数在线上用几个单位显示

相关代码见例3.7

例3.4 绘制多条线段

#include <windows.h>  #include <math.h>  #include <GL\GL.h>  #include <GL\GLU.h>  #include <GL\glut.h>  // Define a constant for the value of PI  #define GL_PI 3.1415f  // This function does any needed initialization on the rendering  void RenderScene(void){GLfloat x, y, z, angle; // Storage for coordinates and angles  GLfloat sizes[2]; // Store supported point size range  GLfloat step; // Store supported point size increments  GLfloat curSize; // Store current point size  // Clear the window with current clearing color  glClear(GL_COLOR_BUFFER_BIT);// Save matrix state and do the rotation  glPushMatrix();//glRotatef(30.0f, 1.0f, 0.0f, 0.0f);//书中的xRot代表x轴偏移的角度  //glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//书中的yRot代表y轴偏移的角度  // Get supported point size range and step size  glGetFloatv(GL_POINT_SIZE_RANGE, sizes);glGetFloatv(GL_POINT_SIZE_GRANULARITY, &step);// Set the initial point size  curSize = sizes[0];// Set beginning z coordinate  z = -50.0f;// Call only once for all remaining points  // Call only once for all remaining pointsglBegin(GL_LINES);// All lines lie in the xy plane.z = 0.0f;for (angle = 0.0f; angle <= GL_PI; angle += (GL_PI / 20.0f)){// Top half of the circlex = 50.0f*sin(angle);y = 50.0f*cos(angle);glVertex3f(x, y, z); // First endpoint of line// Bottom half of the circlex = 50.0f*sin(angle + GL_PI);y = 50.0f*cos(angle + GL_PI);glVertex3f(x, y, z); // Second endpoint of line}// Done drawing pointsglEnd();// Restore transformations  glPopMatrix();// Flush drawing commands  glutSwapBuffers();}void SetupRC(){// Black background  glClearColor(0.0f, 0.0f, 0.0f, 1.0f);// Set drawing color to green  glColor3f(0.0f, 1.0f, 0.0f);}void ChangeSize(GLsizei w, GLsizei h){GLfloat nRange = 100.0f;// Prevent a divide by zero  if (h == 0)h = 1;// Set Viewport to window dimensions  glViewport(0, 0, w, h);// Reset projection matrix stack  glMatrixMode(GL_PROJECTION);glLoadIdentity();// Establish clipping volume (left, right, bottom, top, near, far)  if (w <= h)glOrtho(-nRange, nRange, -nRange*h / w, nRange*h / w, -nRange, nRange);elseglOrtho(-nRange*w / h, nRange*w / h, -nRange, nRange, -nRange, nRange);// Reset Model view matrix stack  glMatrixMode(GL_MODELVIEW);glLoadIdentity();}int main(int argc, char* argv[]){glutInit(&argc, argv);glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);glutInitWindowSize(800, 600);glutCreateWindow("Bounce");glutDisplayFunc(RenderScene);//显示回调函数  glutReshapeFunc(ChangeSize);//窗口大小变形回调函数  SetupRC();glutMainLoop();return 0;}

例3.5 点连曲线

#include <windows.h>  #include <math.h>  #include <GL\GL.h>  #include <GL\GLU.h>  #include <GL\glut.h>  // Define a constant for the value of PI  #define GL_PI 3.1415f  // This function does any needed initialization on the rendering  void RenderScene(void){GLfloat x, y, z, angle; // Storage for coordinates and angles  GLfloat sizes[2]; // Store supported point size range  GLfloat step; // Store supported point size increments  GLfloat curSize; // Store current point size  // Clear the window with current clearing color  glClear(GL_COLOR_BUFFER_BIT);// Save matrix state and do the rotation  glPushMatrix();glRotatef(30.0f, 1.0f, 0.0f, 0.0f);//书中的xRot代表x轴偏移的角度  glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//书中的yRot代表y轴偏移的角度  // Get supported point size range and step size  glGetFloatv(GL_POINT_SIZE_RANGE, sizes);glGetFloatv(GL_POINT_SIZE_GRANULARITY, &step);// Set the initial point size  curSize = sizes[0];// Set beginning z coordinate  z = -50.0f;// Call only once for all remaining points  // Call only once for all remaining pointsglBegin(GL_LINE_STRIP);z = -50.0f;for (angle = 0.0f; angle <= (2.0f*GL_PI)*3.0f; angle += 0.1f){x = 50.0f*sin(angle);y = 50.0f*cos(angle);// Specify the point and move the z value up a littleglVertex3f(x, y, z);z += 0.5f;}// Done drawing pointsglEnd();// Restore transformations  glPopMatrix();// Flush drawing commands  glutSwapBuffers();}void SetupRC(){// Black background  glClearColor(0.0f, 0.0f, 0.0f, 1.0f);// Set drawing color to green  glColor3f(0.0f, 1.0f, 0.0f);}void ChangeSize(GLsizei w, GLsizei h){GLfloat nRange = 100.0f;// Prevent a divide by zero  if (h == 0)h = 1;// Set Viewport to window dimensions  glViewport(0, 0, w, h);// Reset projection matrix stack  glMatrixMode(GL_PROJECTION);glLoadIdentity();// Establish clipping volume (left, right, bottom, top, near, far)  if (w <= h)glOrtho(-nRange, nRange, -nRange*h / w, nRange*h / w, -nRange, nRange);elseglOrtho(-nRange*w / h, nRange*w / h, -nRange, nRange, -nRange, nRange);// Reset Model view matrix stack  glMatrixMode(GL_MODELVIEW);glLoadIdentity();}int main(int argc, char* argv[]){glutInit(&argc, argv);glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);glutInitWindowSize(800, 600);glutCreateWindow("Bounce");glutDisplayFunc(RenderScene);//显示回调函数  glutReshapeFunc(ChangeSize);//窗口大小变形回调函数  SetupRC();glutMainLoop();return 0;}

例3.6 调整线宽度

#include <windows.h>  #include <math.h>  #include <GL\GL.h>  #include <GL\GLU.h>  #include <GL\glut.h>  // Define a constant for the value of PI  #define GL_PI 3.1415f  // This function does any needed initialization on the rendering  void RenderScene(void){GLfloat y; // Storage for varying Y coordinateGLfloat fSizes[2]; // Line width range metricsGLfloat fCurrSize; // Save current size// Clear the window with current clearing color  glClear(GL_COLOR_BUFFER_BIT);// Save matrix state and do the rotation  glPushMatrix();//glRotatef(30.0f, 1.0f, 0.0f, 0.0f);//书中的xRot代表x轴偏移的角度  //glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//书中的yRot代表y轴偏移的角度  // Get supported point size range and step size  glGetFloatv(GL_LINE_WIDTH_RANGE, fSizes);fCurrSize = fSizes[0];// Set the initial point size  // Step up y axis 20 units at a timefor (y = -90.0f; y < 90.0f; y += 20.0f){// Set the line widthglLineWidth(fCurrSize);// Draw the lineglBegin(GL_LINES);glVertex2f(-80.0f, y);glVertex2f(80.0f, y);glEnd();// Increase the line widthfCurrSize += 1.0f;}// Restore transformations  glPopMatrix();// Flush drawing commands  glutSwapBuffers();}void SetupRC(){// Black background  glClearColor(0.0f, 0.0f, 0.0f, 1.0f);// Set drawing color to green  glColor3f(0.0f, 1.0f, 0.0f);}void ChangeSize(GLsizei w, GLsizei h){GLfloat nRange = 100.0f;// Prevent a divide by zero  if (h == 0)h = 1;// Set Viewport to window dimensions  glViewport(0, 0, w, h);// Reset projection matrix stack  glMatrixMode(GL_PROJECTION);glLoadIdentity();// Establish clipping volume (left, right, bottom, top, near, far)  if (w <= h)glOrtho(-nRange, nRange, -nRange*h / w, nRange*h / w, -nRange, nRange);elseglOrtho(-nRange*w / h, nRange*w / h, -nRange, nRange, -nRange, nRange);// Reset Model view matrix stack  glMatrixMode(GL_MODELVIEW);glLoadIdentity();}int main(int argc, char* argv[]){glutInit(&argc, argv);glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);glutInitWindowSize(800, 600);glutCreateWindow("Bounce");glutDisplayFunc(RenderScene);//显示回调函数  glutReshapeFunc(ChangeSize);//窗口大小变形回调函数  SetupRC();glutMainLoop();return 0;}

例3.7 自定义模板绘制虚线

#include <windows.h>  #include <math.h>  #include <GL\GL.h>  #include <GL\GLU.h>  #include <GL\glut.h>  // Define a constant for the value of PI  #define GL_PI 3.1415f  // This function does any needed initialization on the rendering  void RenderScene(void){GLfloat y; // Storage for varying y coordinateGLint factor = 1; // Stippling factorGLushort pattern = 0x5555; // Stipple pattern// Clear the window with current clearing color  glClear(GL_COLOR_BUFFER_BIT);// Save matrix state and do the rotation  glPushMatrix();//glRotatef(30.0f, 1.0f, 0.0f, 0.0f);//书中的xRot代表x轴偏移的角度  //glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//书中的yRot代表y轴偏移的角度  // Get supported point size range and step size  glEnable(GL_LINE_STIPPLE);// Step up Y axis 20 units at a timefor (y = -90.0f; y < 90.0f; y += 20.0f){// Reset the repeat factor and patternglLineStipple(factor, pattern);// Draw the lineglBegin(GL_LINES);glVertex2f(-80.0f, y);glVertex2f(80.0f, y);glEnd();factor++;}// Restore transformations  glPopMatrix();// Flush drawing commands  glutSwapBuffers();}void SetupRC(){// Black background  glClearColor(0.0f, 0.0f, 0.0f, 1.0f);// Set drawing color to green  glColor3f(0.0f, 1.0f, 0.0f);}void ChangeSize(GLsizei w, GLsizei h){GLfloat nRange = 100.0f;// Prevent a divide by zero  if (h == 0)h = 1;// Set Viewport to window dimensions  glViewport(0, 0, w, h);// Reset projection matrix stack  glMatrixMode(GL_PROJECTION);glLoadIdentity();// Establish clipping volume (left, right, bottom, top, near, far)  if (w <= h)glOrtho(-nRange, nRange, -nRange*h / w, nRange*h / w, -nRange, nRange);elseglOrtho(-nRange*w / h, nRange*w / h, -nRange, nRange, -nRange, nRange);// Reset Model view matrix stack  glMatrixMode(GL_MODELVIEW);glLoadIdentity();}int main(int argc, char* argv[]){glutInit(&argc, argv);glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);glutInitWindowSize(800, 600);glutCreateWindow("Bounce");glutDisplayFunc(RenderScene);//显示回调函数  glutReshapeFunc(ChangeSize);//窗口大小变形回调函数  SetupRC();glutMainLoop();return 0;}