OpenGL案例-公转和自转
2020-07-19 本文已影响0人
Sheisone
一、案例效果：
本地案例算是对前面所学习内容的一次总结，实现步骤如下：
绘制地板->绘制大小球-> 让大球自转，小球围绕大球公转 -> 移动观察者
最终效果如下：
案例效果.gif
二、代码解析：
.代码流程和之前一样，仍然会用到之前几个函数，如果同学忘记了或者没有印象的话可以看下这篇文章传送门，接下来我们就开始
1.完成地板的绘制
这一步熟悉之前的案例应该比较简答，我们要实现的效果是用绿色的线绘制一个网格地板，效果图如下：
地板.png
代码如下：
//001--综合训练(地板)
GLShaderManager shaderManager; // 着色器管理器
GLMatrixStack modelViewMatrix; // 模型视图矩阵
GLMatrixStack projectionMatrix; // 投影矩阵
GLFrustum viewFrustum; // 视景体
GLGeometryTransform transformPipeline; // 几何图形变换管道
GLTriangleBatch torusBatch; //大球
GLTriangleBatch sphereBatch; //小球
GLBatch floorBatch; //地板
//角色帧 照相机角色帧
GLFrame cameraFrame;
//**4、添加附加随机球
#define NUM_SPHERES 50
GLFrame spheres[NUM_SPHERES];
void SetupRC()
{
//1.初始化
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
shaderManager.InitializeStockShaders();
//2.开启深度测试
glEnable(GL_DEPTH_TEST);
//3. 设置地板顶点数据
floorBatch.Begin(GL_LINES, 324);
for(GLfloat x = -20.0; x <= 20.0f; x+= 0.5) {
floorBatch.Vertex3f(x, -0.55f, 20.0f);
floorBatch.Vertex3f(x, -0.55f, -20.0f);
floorBatch.Vertex3f(20.0f, -0.55f, x);
floorBatch.Vertex3f(-20.0f, -0.55f, x);
}
floorBatch.End();
}
//进行调用以绘制场景
void RenderScene(void)
{
//1.颜色值(地板,大球,小球颜色)
static GLfloat vFloorColor[] = { 0.0f, 1.0f, 0.0f, 1.0f};
//2.清除颜色缓存区和深度缓冲区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//3.绘制地面
shaderManager.UseStockShader(GLT_SHADER_FLAT,
transformPipeline.GetModelViewProjectionMatrix(),
vFloorColor);
floorBatch.Draw();
//4.执行缓存区交换
glutSwapBuffers();
}
//屏幕更改大小或已初始化
void ChangeSize(int nWidth, int nHeight)
{
//1.设置视口
glViewport(0, 0, nWidth, nHeight);
//2.创建投影矩阵，。
viewFrustum.SetPerspective(35.0f, float(nWidth)/float(nHeight), 1.0f, 100.0f);
//viewFrustum.GetProjectionMatrix() 获取viewFrustum投影矩阵
//并将其加载到投影矩阵堆栈上
projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
//3.设置变换管道以使用两个矩阵堆栈（变换矩阵modelViewMatrix ，投影矩阵projectionMatrix）
//初始化GLGeometryTransform 的实例transformPipeline.通过将它的内部指针设置为模型视图矩阵堆栈 和 投影矩阵堆栈实例，来完成初始化
//当然这个操作也可以在SetupRC 函数中完成，但是在窗口大小改变时或者窗口创建时设置它们并没有坏处。而且这样可以一次性完成矩阵和管线的设置。
transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
}
int main(int argc, char* argv[])
{
gltSetWorkingDirectory(argv[0]);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(800,600);
glutCreateWindow("OpenGL SphereWorld");
glutReshapeFunc(ChangeSize);
glutDisplayFunc(RenderScene);
GLenum err = glewInit();
if (GLEW_OK != err) {
fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
return 1;
}
SetupRC();
glutMainLoop();
return 0;
}
2.绘制大小球
这一步主要是修改setupRC和RenderSence中代码：
-
setupRC代码很简答，只是完成大、小球球模型的创建：
void SetupRC()
{
//1.初始化
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
shaderManager.InitializeStockShaders();
//2.开启深度测试
glEnable(GL_DEPTH_TEST);
//3. 设置地板顶点数据
floorBatch.Begin(GL_LINES, 324);
for(GLfloat x = -20.0; x <= 20.0f; x+= 0.5) {
floorBatch.Vertex3f(x, -0.55f, 20.0f);
floorBatch.Vertex3f(x, -0.55f, -20.0f);
floorBatch.Vertex3f(20.0f, -0.55f, x);
floorBatch.Vertex3f(-20.0f, -0.55f, x);
}
floorBatch.End();
//4.设置大球模型
gltMakeSphere(torusBatch, 0.4f, 40, 80);
//5. 设置小球球模型
gltMakeSphere(sphereBatch, 0.1f, 13, 26);
//6. 随机位置放置小球球
for (int i = 0; i < NUM_SPHERES; i++) {
//y轴不变，X,Z产生随机值
GLfloat x = ((GLfloat)((rand() % 400) - 200 ) * 0.1f);
GLfloat z = ((GLfloat)((rand() % 400) - 200 ) * 0.1f);
//在y方向，将球体设置为0.0的位置，这使得它们看起来是飘浮在眼睛的高度
//对spheres数组中的每一个顶点，设置顶点数据
spheres[i].SetOrigin(x, 0.0f, z);
}
}
-
RenderSence中主要负责完成大小球的绘制，并且将相关矩阵进行压栈和出栈。对矩阵栈不熟悉的朋友可以看下这篇文章传送门
//进行调用以绘制场景
void RenderScene(void)
{
//1.颜色值(地板,大球,小球颜色)
static GLfloat vFloorColor[] = { 0.0f, 1.0f, 0.0f, 1.0f};
static GLfloat vTorusColor[] = { 1.0f, 0.5f, 0.0f, 1.0f};
static GLfloat vSphereColor[] = { 0.0f, 0.5f, 1.0f, 1.0f};
//2.基于时间动画
static CStopWatch rotTimer;
float yRot = rotTimer.GetElapsedSeconds() * 60.0f;
//3.清除颜色缓存区和深度缓冲区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
modelViewMatrix.PushMatrix();
//4.绘制地面
shaderManager.UseStockShader(GLT_SHADER_FLAT,
transformPipeline.GetModelViewProjectionMatrix(),
vFloorColor);
floorBatch.Draw();
//5.获取光源位置
M3DVector4f vLightPos = {0.0f,10.0f,5.0f,1.0f};
//6.使得大球位置平移(3.0)向屏幕里面
modelViewMatrix.Translate(0.0f, 0.0f, -3.0f);
//7.压栈(复制栈顶)
modelViewMatrix.PushMatrix();
//8.大球自转
modelViewMatrix.Rotate(yRot, 0.0f, 1.0f, 0.0f);
//9.指定合适的着色器(点光源着色器)
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF, transformPipeline.GetModelViewMatrix(),
transformPipeline.GetProjectionMatrix(), vLightPos, vTorusColor);
torusBatch.Draw();
//10.绘制完毕则Pop
modelViewMatrix.PopMatrix();
//11.画小球
for (int i = 0; i < NUM_SPHERES; i++) {
modelViewMatrix.PushMatrix();
modelViewMatrix.MultMatrix(spheres[i]);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF, transformPipeline.GetModelViewMatrix(),
transformPipeline.GetProjectionMatrix(), vLightPos, vSphereColor);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
}
modelViewMatrix.PopMatrix();
//12.执行缓存区交换
glutSwapBuffers();
glutPostRedisplay();
}
运行一下，结果如下：
大小球创建.png
3.大球自转和小球围绕大球公转：
这一步我们只修改RenderSence中部分代码即可：
//进行调用以绘制场景
void RenderScene(void)
{
//1.颜色值(地板,大球,小球颜色)
static GLfloat vFloorColor[] = { 0.0f, 1.0f, 0.0f, 1.0f};
static GLfloat vTorusColor[] = { 1.0f, 0.5f, 0.0f, 1.0f};
static GLfloat vSphereColor[] = { 0.0f, 0.5f, 1.0f, 1.0f};
//2.基于时间动画
static CStopWatch rotTimer;
float yRot = rotTimer.GetElapsedSeconds() * 60.0f;
//3.清除颜色缓存区和深度缓冲区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
modelViewMatrix.PushMatrix();
//5.绘制地面
shaderManager.UseStockShader(GLT_SHADER_FLAT,
transformPipeline.GetModelViewProjectionMatrix(),
vFloorColor);
floorBatch.Draw();
//6.获取光源位置
M3DVector4f vLightPos = {0.0f,10.0f,5.0f,1.0f};
//7.使得大球位置平移(3.0)向屏幕里面
modelViewMatrix.Translate(0.0f, 0.0f, -3.0f);
//8.压栈(复制栈顶)
modelViewMatrix.PushMatrix();
//9.大球自转
modelViewMatrix.Rotate(yRot, 0.0f, 1.0f, 0.0f);
//10.指定合适的着色器(点光源着色器)
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF, transformPipeline.GetModelViewMatrix(),
transformPipeline.GetProjectionMatrix(), vLightPos, vTorusColor);
torusBatch.Draw();
//11.绘制完毕则Pop
modelViewMatrix.PopMatrix();
//12.画小球
for (int i = 0; i < NUM_SPHERES; i++) {
modelViewMatrix.PushMatrix();
modelViewMatrix.MultMatrix(spheres[i]);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF, transformPipeline.GetModelViewMatrix(),
transformPipeline.GetProjectionMatrix(), vLightPos, vSphereColor);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
}
//13. 让一个小篮球围绕大球公众自转
modelViewMatrix.Rotate(yRot * -2.0f, 0.0f, 1.0f, 0.0f);
modelViewMatrix.Translate(0.8f, 0.0f, 0.0f);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF,transformPipeline.GetModelViewMatrix(),transformPipeline.GetProjectionMatrix(),vLightPos,vSphereColor);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
//14.执行缓存区交换
glutSwapBuffers();
glutPostRedisplay();
}
-
运行结果如下：
大球自转，小球公转.gif
值得注意的是：我们在让蓝球实现公转的效果的时候，并没有进行矩阵栈的操作，这是因为这个蓝球的绘制是所有图形绘制过程中最后一个，在它之后我们会pop掉矩阵栈中所有的矩阵，所以可以不对它进行矩阵的push和pop，当然你也可以选择增加push和pop，但是请注意位置必须要正确。
代码如下：
modelViewMatrix.PushMatrix();
modelViewMatrix.Rotate(yRot * -2.0f, 0.0f, 1.0f, 0.0f);
modelViewMatrix.Translate(0.8f, 0.0f, 0.0f);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF,transformPipeline.GetModelViewMatrix(),transformPipeline.GetProjectionMatrix(),vLightPos,vSphereColor);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
4.增加移动逻辑
- 在
main函数中注册SpeacialKeys函数：
glutSpecialFunc(SpeacialKeys);
- 然后在
SpeacialKeys中实现上下左右键对观察者的控制：
void SpeacialKeys(int key,int x,int y){
//移动步长
float linear = 0.1f;
//旋转度数
float angular = float(m3dDegToRad(5.0f));
if (key == GLUT_KEY_UP) {
//MoveForward 平移
cameraFrame.MoveForward(linear);
}
if (key == GLUT_KEY_DOWN) {
cameraFrame.MoveForward(-linear);
}
if (key == GLUT_KEY_LEFT) {
//RotateWorld 旋转
cameraFrame.RotateWorld(angular, 0.0f, 1.0f, 0.0f);
}
if (key == GLUT_KEY_RIGHT) {
cameraFrame.RotateWorld(-angular, 0.0f, 1.0f, 0.0f);
}
}
- 在
RenderSence中加入观察者，并进行矩阵栈的push和pop操作：
//进行调用以绘制场景
void RenderScene(void)
{
//1.颜色值(地板,大球,小球颜色)
static GLfloat vFloorColor[] = { 0.0f, 1.0f, 0.0f, 1.0f};
static GLfloat vTorusColor[] = { 1.0f, 0.5f, 0.0f, 1.0f};
static GLfloat vSphereColor[] = { 0.0f, 0.5f, 1.0f, 1.0f};
//2.基于时间动画
static CStopWatch rotTimer;
float yRot = rotTimer.GetElapsedSeconds() * 60.0f;
//3.清除颜色缓存区和深度缓冲区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
modelViewMatrix.PushMatrix();
//4.加入观察者 平移10步(地板,大球,小球,小小球)
M3DMatrix44f mCamera;
cameraFrame.GetCameraMatrix(mCamera);
modelViewMatrix.PushMatrix(mCamera);
//5.获取光源位置
M3DVector4f vLightPos = {0.0f,10.0f,5.0f,1.0f};
//6.绘制地面
shaderManager.UseStockShader(GLT_SHADER_FLAT,
transformPipeline.GetModelViewProjectionMatrix(),
vFloorColor);
floorBatch.Draw();
//大球默认位置(0,0,0)Z深度(3.0) 正负指的是方向, 数字指的移动距离
//7.使得大球位置平移(3.0)向屏幕里面 只移动1次
modelViewMatrix.Translate(0.0f, 0.0f,-3.0f);
//8.压栈(复制栈顶)
modelViewMatrix.PushMatrix();
//9.大球自转
modelViewMatrix.Rotate(yRot, 0.0f, 1.0f, 0.0f);
//10.指定合适的着色器(点光源着色器)
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF, transformPipeline.GetModelViewMatrix(),
transformPipeline.GetProjectionMatrix(), vLightPos, vTorusColor);
torusBatch.Draw();
//11.绘制完毕则Pop
modelViewMatrix.PopMatrix();
//12.画小球
for (int i = 0; i < NUM_SPHERES; i++) {
modelViewMatrix.PushMatrix();
modelViewMatrix.MultMatrix(spheres[i]);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF, transformPipeline.GetModelViewMatrix(),
transformPipeline.GetProjectionMatrix(), vLightPos, vSphereColor);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
}
//13. 让一个小篮球围绕大球公众自转
modelViewMatrix.Rotate(yRot * -2.0f, 0.0f, 1.0f, 0.0f);
modelViewMatrix.Translate(0.8f, 0.0f, 0.0f);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF,transformPipeline.GetModelViewMatrix(),transformPipeline.GetProjectionMatrix(),vLightPos,vSphereColor);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
modelViewMatrix.PopMatrix();
//14.执行缓存区交换
glutSwapBuffers();
//15
glutPostRedisplay();
}
ok,接下来运行工程，按上下左右的时候，观察者就就会进行的相应的移动了。
5.完整代码：
GLShaderManager shaderManager; // 着色器管理器
GLMatrixStack modelViewMatrix; // 模型视图矩阵堆栈
GLMatrixStack projectionMatrix; // 投影矩阵堆栈
GLFrustum viewFrustum; // 视景体
GLGeometryTransform transformPipeline; // 几何图形变换管道
GLTriangleBatch torusBatch; //大球
GLTriangleBatch sphereBatch; //小球
GLBatch floorBatch; //地板
//角色帧 照相机角色帧
GLFrame cameraFrame;
GLFrame objectFrame;
//**4、添加附加随机球
#define NUM_SPHERES 50
GLFrame spheres[NUM_SPHERES];
void SetupRC()
{
//1. 初始化
glClearColor(0, 0, 0, 1);
shaderManager.InitializeStockShaders();
glEnable(GL_DEPTH_TEST);
//3. 地板数据(物体坐标系)
floorBatch.Begin(GL_LINES, 324);
for(GLfloat x = -20.0; x <= 20.0f; x+= 0.5) {
floorBatch.Vertex3f(x, -0.55f, 20.0f);
floorBatch.Vertex3f(x, -0.55f, -20.0f);
floorBatch.Vertex3f(20.0f, -0.55f, x);
floorBatch.Vertex3f(-20.0f, -0.55f, x);
}
floorBatch.End();
//4. 设置一个球体(基于gltools模型)
gltMakeSphere(torusBatch, 0.4f, 40, 80);
//5. 绘制小球;
gltMakeSphere(sphereBatch, 0.1f, 30, 60);
//6. 随机位置放置小球球
for (int i = 0; i < NUM_SPHERES; i++) {
//y轴不变，X,Z产生随机值
GLfloat x = ((GLfloat)((rand() % 400) - 200 ) * 0.1f);
GLfloat z = ((GLfloat)((rand() % 400) - 200 ) * 0.1f);
//在y方向，将球体设置为0.0的位置，这使得它们看起来是飘浮在眼睛的高度
//对spheres数组中的每一个顶点，设置顶点数据
spheres[i].SetOrigin(x, 0.0f, z);
}
}
//进行调用以绘制场景
void RenderScene(void)
{
//3.
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//1. 颜色(地板,大球颜色,小球颜色)
static GLfloat vFloorColor[] = {0.0f,1.0f,0.0f,1.0f};
static GLfloat vTorusColor[] = {1.0f,0.5f,0.0f,1.0f};
static GLfloat vSpereColor[] = {0.0f,0.5f,1.0f,1.0f};
//2. 动画
static CStopWatch rotTimer;
float yRot = rotTimer.GetElapsedSeconds()*60.0f;
modelViewMatrix.PushMatrix();
M3DMatrix44f mCamera;
cameraFrame.GetCameraMatrix(mCamera);
modelViewMatrix.PushMatrix(mCamera);
//4.地面绘制;
shaderManager.UseStockShader(GLT_SHADER_FLAT,transformPipeline.GetModelViewProjectionMatrix(),vFloorColor);
floorBatch.Draw();
//5. 设置点光源位置
M3DVector4f vLightPos = {0,10,5,1};
//6. 使得整个大球往里平移3.0
modelViewMatrix.Translate(0.0f, 0.0f, -3.0f);
//7. 大球
modelViewMatrix.PushMatrix();
modelViewMatrix.Rotate(yRot, 0, 1, 0);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF,transformPipeline.GetModelViewMatrix(),transformPipeline.GetProjectionMatrix(),vLightPos,vTorusColor);
torusBatch.Draw();
modelViewMatrix.PopMatrix();
//8. 小球
for (int i = 0; i < NUM_SPHERES; i++) {
modelViewMatrix.PushMatrix();
modelViewMatrix.MultMatrix(spheres[i]);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF,transformPipeline.GetModelViewMatrix(),transformPipeline.GetProjectionMatrix(),vLightPos,vSpereColor);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
}
//9.让一个小球围着大球公转;
modelViewMatrix.Rotate(yRot * -2.0f, 0, 1, 0);
modelViewMatrix.Translate(0.8f, 0.0f, 0.0f);
shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF,transformPipeline.GetModelViewMatrix(),transformPipeline.GetProjectionMatrix(),vLightPos,vSpereColor);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
modelViewMatrix.PopMatrix();
glutSwapBuffers();
glutPostRedisplay();
}
//屏幕更改大小或已初始化
void ChangeSize(int nWidth, int nHeight)
{
//1. 设置视口
glViewport(0, 0, nWidth, nHeight);
//2. 创建投影矩阵
viewFrustum.SetPerspective(35.0f, float(nWidth)/float(nHeight), 1.0f, 100.0f);
projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
//3. 变换管道设置2个矩阵堆栈(管理)
transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
}
void SpeacialKeys(int key,int x,int y){
float linear = 0.1f;
float angular = float(m3dDegToRad(5.0f));
if (key == GLUT_KEY_UP) {
cameraFrame.MoveForward(linear);
}
if (key == GLUT_KEY_DOWN) {
cameraFrame.MoveForward(-linear);
}
if (key == GLUT_KEY_LEFT) {
cameraFrame.RotateWorld(angular, 0, 1, 0);
}
if (key == GLUT_KEY_RIGHT) {
cameraFrame.RotateWorld(-angular, 0, 1, 0);
}
}
int main(int argc, char* argv[])
{
gltSetWorkingDirectory(argv[0]);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(800,600);
glutCreateWindow("OpenGL SphereWorld");
glutReshapeFunc(ChangeSize);
glutDisplayFunc(RenderScene);
glutSpecialFunc(SpeacialKeys);
GLenum err = glewInit();
if (GLEW_OK != err) {
fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
return 1;
}
SetupRC();
glutMainLoop();
return 0;
}
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