加入了按键来控制方块的移动,通过改变方块的位置然后刷新屏幕来实现,基本原理其实也很简单。
前面已经注释过的这里可能没有进一步注释了 。
#include <GLTools.h> // OpenGL toolkit
#include <GLShaderManager.h>
#define FREEGLUT_STATIC //在windows和linux上,使用freeglut静态版本,需要添加这一行,否则会出现错误
#include <glut.h>
#pragma comment(lib,"gltools.lib")//要加上这一行链接一下gltools库
GLShaderManager shaderManager;//着色器管理器
GLBatch squareBatch;//用来绘制基本的方形图元
GLfloat blockSize = 0.1f;//方块的大小
GLfloat vVerts[] = { -blockSize, -blockSize, 0.0f,
blockSize, -blockSize, 0.0f,
blockSize, blockSize, 0.0f,
-blockSize, blockSize, 0.0f };//设置方块的四个坐标点
void SetupRC()
{
glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
shaderManager.InitializeStockShaders();
// Load up a triangle
squareBatch.Begin(GL_TRIANGLE_FAN, 4);
squareBatch.CopyVertexData3f(vVerts);
squareBatch.End();
}
void SpecialKeys(int key, int x, int y)
{
GLfloat stepSize = 0.025f;//每次移动的步长
GLfloat blockX = vVerts[0]; // 方形左边的x坐标
GLfloat blockY = vVerts[7]; // 方形上边的y坐标
if (key == GLUT_KEY_UP)
blockY += stepSize;
if (key == GLUT_KEY_DOWN)
blockY -= stepSize;
if (key == GLUT_KEY_LEFT)
blockX -= stepSize;
if (key == GLUT_KEY_RIGHT)
blockX += stepSize;
// Collision detection
if (blockX < -1.0f) blockX = -1.0f;//x小于左边界,x不能继续移动,保持原位
if (blockX >(1.0f - blockSize * 2)) blockX = 1.0f - blockSize * 2;//根据坐标关系,方形边长为2*blockSize,这样可以保证右边界不越界
if (blockY < -1.0f + blockSize * 2) blockY = -1.0f + blockSize * 2;//保证左边界不越界
if (blockY > 1.0f) blockY = 1.0f;//y大于上边界,保持原位
// Recalculate vertex positions
vVerts[0] = blockX;
vVerts[1] = blockY - blockSize * 2;
vVerts[3] = blockX + blockSize * 2;
vVerts[4] = blockY - blockSize * 2;
vVerts[6] = blockX + blockSize * 2;
vVerts[7] = blockY;
vVerts[9] = blockX;
vVerts[10] = blockY;
squareBatch.CopyVertexData3f(vVerts);
glutPostRedisplay();//刷新屏幕
}
void RenderScene(void)
{
// Clear the window with current clearing color
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
GLfloat vRed[] = { 1.0f, 0.0f, 0.0f, 1.0f };
shaderManager.UseStockShader(GLT_SHADER_IDENTITY, vRed);
squareBatch.Draw();
// Flush drawing commands
glutSwapBuffers();
}
void ChangeSize(int w, int h)
{
glViewport(0, 0, w, h);
}
int main(int argc, char* argv[])
{
gltSetWorkingDirectory(argv[0]);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
glutInitWindowSize(800, 600);
glutCreateWindow("Move Block with Arrow Keys");
GLenum err = glewInit();
if (GLEW_OK != err)
{
// Problem: glewInit failed, something is seriously wrong.
fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
return 1;
}
glutReshapeFunc(ChangeSize);
glutDisplayFunc(RenderScene);
glutSpecialFunc(SpecialKeys);//注册按键消息
SetupRC();
glutMainLoop();
return 0;
}