OpenGL 学习笔记3_1(绘制点相关)

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蓝宝书第三章

画点 Point

1）单个点

glVertex3f(50.0f,50.0f,0.0f) 3D图像的点

glVertex2f(50.0f,50.0f) 2D图像的点

2）多个点

glBegin(GL_POINTS)

……

glEnd();

相关代码见例3.3

例3.1 窗口改变响应函数--3D版

void ChangeSize(GLsizei w, GLsizei h){GLfloat nRange = 100.0f;// Prevent a divide by zeroif (h == 0)h = 1;// Set Viewport to window dimensionsglViewport(0, 0, w, h);// Reset projection matrix stackglMatrixMode(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 stackglMatrixMode(GL_MODELVIEW);glLoadIdentity();}

例3.2 显示多个点

#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 renderingvoid RenderScene(void){GLfloat x, y, z, angle; // Storage for coordinates and angles// Clear the window with current clearing colorglClear(GL_COLOR_BUFFER_BIT);// Save matrix state and do the rotationglPushMatrix();glRotatef(30.0f, 1.0f, 0.0f, 0.0f);//书中的xRot代表x轴偏移的角度，此处改为x轴偏移30度glRotatef(30.0f, 0.0f, 1.0f, 0.0f);//书中的yRot代表y轴偏移的角度，此处改为y轴偏移30度// Call only once for all remaining pointsglBegin(GL_POINTS);z = -50.0f;for (angle = 0.0f; angle <= (2.0f*GL_PI)*3.0f; angle += 0.1f){x = 50.0f*sin(angle);//sin输入为弧度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 transformationsglPopMatrix();// Flush drawing commandsglutSwapBuffers();}void SetupRC(){// Black backgroundglClearColor(0.0f, 0.0f, 0.0f, 1.0f);// Set drawing color to greenglColor3f(0.0f, 1.0f, 0.0f);}void ChangeSize(GLsizei w, GLsizei h){GLfloat nRange = 100.0f;// Prevent a divide by zeroif (h == 0)h = 1;// Set Viewport to window dimensionsglViewport(0, 0, w, h);// Reset projection matrix stackglMatrixMode(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 stackglMatrixMode(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3.3 点大小的改变

#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 renderingvoid RenderScene(void){GLfloat x, y, z, angle; // Storage for coordinates and anglesGLfloat sizes[2]; // Store supported point size rangeGLfloat step; // Store supported point size incrementsGLfloat curSize; // Store current point size// Clear the window with current clearing colorglClear(GL_COLOR_BUFFER_BIT);// Save matrix state and do the rotationglPushMatrix();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 sizeglGetFloatv(GL_POINT_SIZE_RANGE, sizes);glGetFloatv(GL_POINT_SIZE_GRANULARITY, &step);// Set the initial point sizecurSize = sizes[0];// Set beginning z coordinatez = -50.0f;// Call only once for all remaining pointsglBegin(GL_POINTS);z = -50.0f;for (angle = 0.0f; angle <= (2.0f*GL_PI)*3.0f; angle += 0.1f){// Calculate x and y values on the circlex = 50.0f*sin(angle);y = 50.0f*cos(angle);// Specify the point size before the primitive is specifiedglPointSize(curSize);// Draw the pointglBegin(GL_POINTS);glVertex3f(x, y, z);glEnd();// Bump up the z value and the point sizez += 0.5f;curSize += step;}// Done drawing pointsglEnd();// Restore transformationsglPopMatrix();// Flush drawing commandsglutSwapBuffers();}void SetupRC(){// Black backgroundglClearColor(0.0f, 0.0f, 0.0f, 1.0f);// Set drawing color to greenglColor3f(0.0f, 1.0f, 0.0f);}void ChangeSize(GLsizei w, GLsizei h){GLfloat nRange = 100.0f;// Prevent a divide by zeroif (h == 0)h = 1;// Set Viewport to window dimensionsglViewport(0, 0, w, h);// Reset projection matrix stackglMatrixMode(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 stackglMatrixMode(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;}

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