1.顶点依次移动
定义边长和顶点数据
//blockSize 边长
GLfloat blockSize = 0.1f;
//正方形的4个点坐标
GLfloat vVerts[] = {//x,y,z
-blockSize,-blockSize,0.0f, //A
blockSize,-blockSize,0.0f, //B
blockSize,blockSize,0.0f, //C
-blockSize,blockSize,0.0f //D
};
以顶点D为例,依次移动每个顶点
void SpecialKeys(int key, int x, int y){
GLfloat stepSize = 0.025f;
//最后一个顶点D
GLfloat blockX = vVerts[0];//vVerts[0]和vVerts[9]相同
GLfloat blockY = vVerts[10];
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;
}
//触碰到边界(4个边界)的处理
//当正方形移动超过最左边的时候
if (blockX < -1.0f) {
blockX = -1.0f;
}
//当正方形移动到最右边时
//1.0 - blockSize * 2 = 总边长 - 正方形的边长 = 最左边点的位置
if (blockX > (1.0 - blockSize * 2)) {
blockX = 1.0f - blockSize * 2;
}
//当正方形移动到最下面时
//-1.0 - blockSize * 2 = Y(负轴边界) - 正方形边长 = 最下面点的位置
if (blockY < -1.0f + blockSize * 2 ) {
blockY = -1.0f + blockSize * 2;
}
//当正方形移动到最上面时
if (blockY > 1.0f) {
blockY = 1.0f;
}
// 计算每个顶点的位置
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;
triangleBatch.CopyVertexData3f(vVerts);
glutPostRedisplay();
}
顶点比较少的话,还能接受,如果是个复杂图形,顶点贼多,这种方法显然不好,我们用矩阵方式来移动
2.矩阵方式移动
定义移动移动距离(可看作中心点)
// 在x轴上平移的距离
GLfloat xPos = 0.0f;
// 在y轴上平移的距离
GLfloat yPos = 0.0f;
绘制的代码
void RenderScene(void) {
/*
清除一个或者一组特定的缓存区
缓冲区是一块存在图像信息的储存空间,红色、绿色、蓝色和alpha分量通常一起分量通常一起作为颜色缓存区或像素缓存区引用。
OpenGL 中不止一种缓冲区(颜色缓存区、深度缓存区和模板缓存区)
GL_COLOR_BUFFER_BIT :指示当前激活的用来进行颜色写入缓冲区
GL_DEPTH_BUFFER_BIT :指示深度缓存区
GL_STENCIL_BUFFER_BIT:指示模板缓冲区
*/
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
//2.设置一组浮点数来表示颜色(RGBA)
GLfloat vRed[] = {1.0f,0.0f,0.0f,0.0f};
//定义矩阵
M3DMatrix44f mFinalTransform,mTransfromMatrix,mRotationMartix;
//平移矩阵
m3dTranslationMatrix44(mTransfromMatrix, xPos, yPos, 0.0f);
//每次平移时,旋转5度
static float yRot = 0.0f;
yRot += 5.0f;
//旋转矩阵
m3dRotationMatrix44(mRotationMartix, m3dDegToRad(yRot), 0.0f, 0.0f, 1.0f);
//将旋转和移动的矩阵结果 合并到mFinalTransform (矩阵相乘)
m3dMatrixMultiply44(mFinalTransform, mTransfromMatrix, mRotationMartix);
//将矩阵结果 提交给固定着色器(平面着色器)中绘制
shaderManager.UseStockShader(GLT_SHADER_FLAT,mFinalTransform,vRed);
triangleBatch.Draw();
//执行交换缓存区
glutSwapBuffers();
}
移动的代码
void SpecialKeys(int key, int x, int y){
// 移动的步长
GLfloat stepSize = 0.025f;
if (key == GLUT_KEY_UP) {
yPos += stepSize;
}
if (key == GLUT_KEY_DOWN) {
yPos -= stepSize;
}
if (key == GLUT_KEY_LEFT) {
xPos -= stepSize;
}
if (key == GLUT_KEY_RIGHT) {
xPos += stepSize;
}
//碰撞检测
if (xPos < (-1.0f + blockSize)) {
xPos = -1.0f + blockSize;
}
if (xPos > (1.0f - blockSize)) {
xPos = 1.0f - blockSize;
}
if (yPos < (-1.0f + blockSize)) {
yPos = -1.0f + blockSize;
}
if (yPos > (1.0f - blockSize)) {
yPos = 1.0f - blockSize;
}
// 提交重绘
glutPostRedisplay();
}