????? 通常我們在xz平面定義一個二維的網格，然后y的值根據一定的函數計算得到，比如正弦、余弦函數的組合等等，可以得到一個看似不錯的地形或者水面的效果。 在本教程中我們修改ModelClass.h和ModelClass.cpp,得到一個近似的地形。

???

??? 在本章代碼中，我們定義300*300=90000個頂點，共(300-1)(300-1)*2個三角形，每個網格的大小都為1.

??? 我們得到y值的函數為：

float ModelClass::getHeight(float x, float z) const
??? {
??? return 0.3f*( z*sinf(0.1f*x) + x*cosf(0.1f*z) );
??? }

????

????

ModelClass.h主要代碼如下：

#pragma once

#include <d3d11.h>
#include <d3dx10math.h>
#include "common.h"

class ModelClass
??? {
…

??????? int GetIndexCount();
?????? //根據頂點的x值和z值，計算出y值
??????? float getHeight(float x, float z)const;

??? private:
??????? bool InitializeBuffers(ID3D11Device*, int, int, float);
??????? void ShutdownBuffers();
??????? void RenderBuffers(ID3D11DeviceContext*);
??????? //頂點緩沖和頂點索引緩沖
??????? ID3D11Buffer *m_vertexBuffer, *m_indexBuffer;
??????? int m_vertexCount, m_indexCount;

??? };

??? ModelClass.cpp主要代碼如下：

bool ModelClass::Initialize(ID3D11Device* device, int m, int n, float dx)
??? {
??? bool result;

??? // 初始化頂點緩沖和頂點索引緩沖.
? ? result = InitializeBuffers(device, m, n, dx);
??? if(!result)
??????? {
??????? return false;
??????? }

??? return true;
??? }

void ModelClass::Shutdown()
??? {
??? // 釋放頂點和索引緩沖.
??? ShutdownBuffers();

??? return;
??? }

float ModelClass::getHeight(float x, float z) const
??? {
??? return 0.3f*( z*sinf(0.1f*x) + x*cosf(0.1f*z) );
??? }

void ModelClass::Render(ID3D11DeviceContext* deviceContext)
??? {
??? // 把頂點和索引緩沖放入圖形管線，準備渲染.
??? RenderBuffers(deviceContext);

??? return;
??? }

int ModelClass::GetIndexCount()
??? {
?? //返回索引頂點計數
??? return m_indexCount;
??? }

bool ModelClass::InitializeBuffers(ID3D11Device* device, int m, int n, float dx)
??? {
??? VertexType* vertices;
??? unsigned long* indices;
??? D3D11_BUFFER_DESC vertexBufferDesc, indexBufferDesc;
??? D3D11_SUBRESOURCE_DATA vertexData, indexData;
??? HRESULT result;

??? //計算得到頂點和索引頂點數目
??? //首先得到三角形的數目，然后乘以3就是頂點索引數目
??? m_vertexCount = m*n;
??? m_indexCount??? = (m-1)*(n-1)*2*3;

??? // 創建頂點臨時緩沖.
??? vertices = new VertexType[m_vertexCount];
??? if(!vertices)
??????? {
??????? return false;
??????? }

??? float halfWidth = (n-1)*dx*0.5f;
??? float halfDepth = (m-1)*dx*0.5f;

??? for(int i = 0; i < m; ++i)
??????? {
??????? float z = halfDepth - i*dx;
??????? for(int j = 0; j < n; ++j)
??????????? {
??????????? float x = -halfWidth + j*dx;

??????????? // 計算得到z值.
??????????? float y = getHeight(x,z);

??????????? vertices[i*n+j].position = D3DXVECTOR3(x, y, z);

??????????? // 根據高度來定義顏色
??????????? if( y < -10.0f )
??????????????? vertices[i*n+j].color = BEACH_SAND;
??????????? else if( y < 5.0f )
??????????????? vertices[i*n+j].color = LIGHT_YELLOW_GREEN;
??????????? else if( y < 12.0f )
??????????????? vertices[i*n+j].color = DARK_YELLOW_GREEN;
??????????? else if( y < 20.0f )
??????????????? vertices[i*n+j].color = DARKBROWN;
??????????? else
??????????????? vertices[i*n+j].color = WHITE;
??????????? }
??????? }

??? // 創建索引緩沖.
??? indices = new unsigned long[m_indexCount];
??? if(!indices)
??????? {
??????? return false;
??????? }

?? // 迭代每個grid，計算得出索引.
??? int k = 0;
??? for(int i = 0; i < m-1; ++i)
??????? {
??????? for(int j = 0; j < n-1; ++j)
??????????? {
??????????? indices[k]?? = i*n+j;
??????????? indices[k+1] = i*n+j+1;
??????????? indices[k+2] = (i+1)*n+j;

??????????? indices[k+3] = (i+1)*n+j;
??????????? indices[k+4] = i*n+j+1;
??????????? indices[k+5] = (i+1)*n+j+1;

??????????? k += 6; //下一個grid
??????????? }
??????? }

??? // 設置頂點緩沖描述

…

??? return true;
??? }

還要修改一下GraphicsClass.cpp中初始化ModelClass的代碼：

// 初始化模型對象.
result = m_Model->Initialize(m_D3D->GetDevice(), 300, 300, 1.0f);
if(!result)
??? {
??? MessageBox(hwnd, L"Could not initialize the model object.", L"Error", MB_OK);
??? return false;
??? }

運行程序后，效果如下，我們還可以用a/s/d/w鍵來移動攝像機看看地形的效果。

我們還可以修改D3DClass.cpp中，渲染狀態Fillmode設置，修改為線框模式后的效果如下：

D3DClass.cpp中修改代碼如下：

// 設置光柵化描述，指定多邊形如何被渲染.
rasterDesc.AntialiasedLineEnable = false;
rasterDesc.CullMode = D3D11_CULL_BACK;
rasterDesc.DepthBias = 0;
rasterDesc.DepthBiasClamp = 0.0f;
rasterDesc.DepthClipEnable = true;
rasterDesc.FillMode = D3D11_FILL_WIREFRAME;
rasterDesc.FrontCounterClockwise = false;
rasterDesc.MultisampleEnable = false;
rasterDesc.ScissorEnable = false;
rasterDesc.SlopeScaledDepthBias = 0.0f;

?

完整的代碼請參考：

工程文件myTutorialD3D11_13

代碼下載：

http://files.cnblogs.com/mikewolf2002/myTutorialD3D11.zip

轉載于:https://www.cnblogs.com/mikewolf2002/archive/2012/03/25/2416405.html

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