藍寶書 第三章
畫線 Line
1）兩點定一條實線
glBegin(GL_LINES);
glVertex3f(……);//點a
glVertex3f(……);//點b
glVertex3f(……);//點c
glVertex3f(……);//點d
glEnd();
繪制線段ab、cd
相關代碼見例3.4
2）繪制連續線段，連接密集的點成曲線
glBegin(GL_LINE_STRip);
glVertex3f(……);//點a
glVertex3f(……);//點b
glVertex3f(……);//點c
glVertex3f(……);//點d
glEnd();
繪制線段ab、bc、cd相關代碼見例3.5
3）設置線寬度voidglLineWidth(GLfloatwidth);設置線寬度
GLfloat sizes[2]; // 存放線寬度的范圍
GLfloat step; // 存放每次改變線寬度的最小增量
glGetFloatv(GL_LINE_WIDTH_RANGE,sizes);//獲取線寬范圍
glGetFloatv(GL_LINE_WIDTH_GRANULARITY,&step);//獲取最小增量
相關代碼見例3.6
4）繪制虛線，自定義虛線模板
glEnable(GL_LINE_STIPPLE);//啟用模板功能
void glLineStipple(GLintfactor, GLushort pattern);//設置影響因子及模板格式
factor代表每位二進制數在線上用幾個單位顯示
相關代碼見例3.7例3.4 繪制多條線段
#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);//書中的xRot代表x軸偏移的角度 //glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//書中的yRot代表y軸偏移的角度 // 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 points glBegin(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 circle x = 50.0f*sin(angle); y = 50.0f*cos(angle); glVertex3f(x, y, z); // First endpoint of line // Bottom half of the circle x = 50.0f*sin(angle + GL_PI); y = 50.0f*cos(angle + GL_PI); glVertex3f(x, y, z); // Second endpoint of line } // Done drawing points glEnd(); // 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); else glOrtho(-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);//顯示回調函數 glutReshapeFunc(ChangeSize);//窗口大小變形回調函數 SetupRC(); glutMainLoop(); return 0;}例3.5 點連曲線#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);//書中的xRot代表x軸偏移的角度 glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//書中的yRot代表y軸偏移的角度 // 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 points glBegin(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 little glVertex3f(x, y, z); z += 0.5f; } // Done drawing points glEnd(); // 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); else glOrtho(-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);//顯示回調函數 glutReshapeFunc(ChangeSize);//窗口大小變形回調函數 SetupRC(); glutMainLoop(); return 0;}例3.6 調整線寬度#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 coordinate GLfloat fSizes[2]; // Line width range metrics GLfloat 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);//書中的xRot代表x軸偏移的角度 //glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//書中的yRot代表y軸偏移的角度 // 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 time for (y = -90.0f; y < 90.0f; y += 20.0f) { // Set the line width glLineWidth(fCurrSize); // Draw the line glBegin(GL_LINES); glVertex2f(-80.0f, y); glVertex2f(80.0f, y); glEnd(); // Increase the line width fCurrSize += 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); else glOrtho(-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);//顯示回調函數 glutReshapeFunc(ChangeSize);//窗口大小變形回調函數 SetupRC(); glutMainLoop(); return 0;}例3.7 自定義模板繪制虛線
#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 coordinate GLint factor = 1; // Stippling factor GLushort 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);//書中的xRot代表x軸偏移的角度 //glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//書中的yRot代表y軸偏移的角度 // Get supported point size range and step size glEnable(GL_LINE_STIPPLE); // Step up Y axis 20 units at a time for (y = -90.0f; y < 90.0f; y += 20.0f) { // Reset the repeat factor and pattern glLineStipple(factor, pattern); // Draw the line glBegin(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); else glOrtho(-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);//顯示回調函數 glutReshapeFunc(ChangeSize);//窗口大小變形回調函數 SetupRC(); glutMainLoop(); return 0;}
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