一、绘制正方形
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定义顶点到原心距离,即 正方形边长 = blockSize * 2
//blockSize 边长
GLfloat blockSize = 0.1f;
修改顶点数组
//正方形的4个点坐标
GLfloat vVerts[] = {
-blockSize,-blockSize,0.0f,
blockSize,-blockSize,0.0f,
blockSize,blockSize,0.0f,
-blockSize,blockSize,0.0f
};
收到渲染消息执行:
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1、清除一个或者一组特定的缓存区
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红色
GLfloat vRed[] = {1.0,0.0,0.0,1.0f};
3、 提交着色器
triangleBatch.Draw();
4、将后台缓冲区进行渲染,然后结束后交换给前台
glutSwapBuffers();
修改setupRC函数中图元的连接方式
设置清屏颜色(背景颜色)
glClearColor(0.98f, 0.40f, 0.7f, 1);
修改为GL_TRIANGLE_FAN ,4个顶点
triangleBatch.Begin(GL_TRIANGLE_FAN, 4);
triangleBatch.CopyVertexData3f(vVerts);
triangleBatch.End();
二、特殊键位移动函数
1、坐标更新方式
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void SpecialKeys(int key, int x, int y){
GLfloat stepSize = 0.025f;
GLfloat blockX = vVerts[0];
GLfloat blockY = vVerts[10];
printf("v[0] = %f\n",blockX);
printf("v[10] = %f\n",blockY);
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;
}
printf("blockX = %f\n",blockX);
printf("blockY = %f\n",blockY);
// Recalculate vertex positions
vVerts[0] = blockX;
vVerts[1] = blockY - blockSize*2;
printf("(%f,%f)\n",vVerts[0],vVerts[1]);
vVerts[3] = blockX + blockSize*2;
vVerts[4] = blockY - blockSize*2;
printf("(%f,%f)\n",vVerts[3],vVerts[4]);
vVerts[6] = blockX + blockSize*2;
vVerts[7] = blockY;
printf("(%f,%f)\n",vVerts[6],vVerts[7]);
vVerts[9] = blockX;
vVerts[10] = blockY;
printf("(%f,%f)\n",vVerts[9],vVerts[10]);
triangleBatch.CopyVertexData3f(vVerts);
glutPostRedisplay();
}
2、矩阵方法
收到消息渲染—>RenderScene函数
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glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
GLfloat vRed[] = {1.0f,0.0f,0.0f,0.0f};
M3DMatrix44f mFinalTransform,mTransfromMatrix,mRotationMartix;
//平移
m3dTranslationMatrix44(mTransfromMatrix, xPos, yPos, 0.0f);
//每次平移时,旋转5度
static float yRot = 0.0f;
yRot += 5.0f;
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();
矩阵方式的SpecialKeys函数
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void SpecialKeys(int key, int x, int y){
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;
}
glutPostRedisplay();
}
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