【DX11地形篇】8-天空球

参考教程

Tutorial 7: Sky Domes

学习记录

  这篇文章中我们介绍天空的绘制，使用 SkyDome 实现。原理就是绘制球体，我们的场景都在球体里面，从场景的位置看向上方就可以看到球的内部面，所以需要我们关闭或者反转背面剔除，然后渲染球体。本篇代码基于上一篇，新增 SkydomeClass 和 SkydomeShaderClass 类。

  SkyDomeClass 其实就是球体模型的类，类似于 TerrainClass ，它负责顶点索引信息的封装，声明如下：

////////////////////////////////////////////////////////////////////////////////
// Class name: SkyDomeClass
////////////////////////////////////////////////////////////////////////////////
class SkyDomeClass
{
private:
	struct ModelType
	{
		float x, y, z;
		float tu, tv;
		float nx, ny, nz;
	};

	struct VertexType
	{
		XMFLOAT3 position;
	};

public:
	SkyDomeClass();
	SkyDomeClass(const SkyDomeClass&);
	~SkyDomeClass();

	bool Initialize(ID3D11Device*);
	void Shutdown();
	void Render(ID3D11DeviceContext*);

	int GetIndexCount();
	XMFLOAT4 GetApexColor();
	XMFLOAT4 GetCenterColor();

private:
	bool LoadSkyDomeModel(char*);
	void ReleaseSkyDomeModel();

	bool InitializeBuffers(ID3D11Device*);
	void ReleaseBuffers();
	void RenderBuffers(ID3D11DeviceContext*);

private:
	ModelType* m_model;
	int m_vertexCount, m_indexCount;
	ID3D11Buffer *m_vertexBuffer, *m_indexBuffer;
	XMFLOAT4 m_apexColor, m_centerColor;
};

  其实现也是很简单，使用 LoadSkyDomeModel 加载模型文件，然后 InitializeBuffers 创建缓冲等等。

  SkyDomeShaderClass 是简单的渲染类，声明如下：

////////////////////////////////////////////////////////////////////////////////
// Class name: SkyDomeShaderClass
////////////////////////////////////////////////////////////////////////////////
class SkyDomeShaderClass
{
private:
	struct MatrixBufferType
	{
		XMMATRIX world;
		XMMATRIX view;
		XMMATRIX projection;
	};

	struct ColorBufferType
	{
		XMFLOAT4 apexColor;
		XMFLOAT4 centerColor;
	};

public:
	SkyDomeShaderClass();
	SkyDomeShaderClass(const SkyDomeShaderClass&);
	~SkyDomeShaderClass();

	bool Initialize(ID3D11Device*, HWND);
	void Shutdown();
	bool Render(ID3D11DeviceContext*, int, XMMATRIX, XMMATRIX, XMMATRIX, XMFLOAT4, XMFLOAT4);

private:
	bool InitializeShader(ID3D11Device*, HWND, CHAR*, CHAR*);
	void ShutdownShader();
	void OutputShaderErrorMessage(ID3D10Blob*, HWND, CHAR*);

	bool SetShaderParameters(ID3D11DeviceContext*, XMMATRIX, XMMATRIX, XMMATRIX, XMFLOAT4, XMFLOAT4);
	void RenderShader(ID3D11DeviceContext*, int);

private:
	ID3D11VertexShader* m_vertexShader;
	ID3D11PixelShader* m_pixelShader;
	ID3D11InputLayout* m_layout;
	ID3D11Buffer* m_matrixBuffer;

	ID3D11Buffer* m_colorBuffer;
};

  其所对应的 skydome.vs 和 skydome.ps 中，其数据的传递和变换类似其他的着色器，着色的时候我们以顶点的高度为分量来计算颜色，如下：

////////////////////////////////////////////////////////////////////////////////
// Filename: skydome.vs
////////////////////////////////////////////////////////////////////////////////


/////////////
// GLOBALS //
/////////////
cbuffer MatrixBuffer
{
    matrix worldMatrix;
    matrix viewMatrix;
    matrix projectionMatrix;
};


//////////////
// TYPEDEFS //
//////////////
struct VertexInputType
{
    float4 position : POSITION;
};

struct PixelInputType
{
    float4 position : SV_POSITION;
    float4 domePosition : TEXCOORD0;
};


////////////////////////////////////////////////////////////////////////////////
// Vertex Shader
////////////////////////////////////////////////////////////////////////////////
PixelInputType SkyDomeVertexShader(VertexInputType input)
{
    PixelInputType output;
    

    // Change the position vector to be 4 units for proper matrix calculations.
    input.position.w = 1.0f;

    // Calculate the position of the vertex against the world, view, and projection matrices.
    output.position = mul(input.position, worldMatrix);
    output.position = mul(output.position, viewMatrix);
    output.position = mul(output.position, projectionMatrix);
    
    // Send the unmodified position through to the pixel shader.
    output.domePosition = input.position;

    return output;
}

////////////////////////////////////////////////////////////////////////////////
// Filename: skydome.ps
////////////////////////////////////////////////////////////////////////////////


/////////////
// GLOBALS //
/////////////
cbuffer ColorBuffer
{
    float4 apexColor;
    float4 centerColor;
};


//////////////
// TYPEDEFS //
//////////////
struct PixelInputType
{
    float4 position : SV_POSITION;
    float4 domePosition : TEXCOORD0;
};


////////////////////////////////////////////////////////////////////////////////
// Pixel Shader
////////////////////////////////////////////////////////////////////////////////
float4 SkyDomePixelShader(PixelInputType input) : SV_TARGET
{
    float height;
    float4 outputColor;


    // Determine the position on the sky dome where this pixel is located.
    height = input.domePosition.y;

    // The value ranges from -1.0f to +1.0f so change it to only positive values.
    if(height < 0.0)
    {
        height = 0.0f;
    }

    // Determine the gradient color by interpolating between the apex and center based on the height of the pixel in the sky dome.
    outputColor = lerp(centerColor, apexColor, height);

    return outputColor;
}

  最后我们在 ZoneClass 里添加 SkyDome 的对象，在 ShaderManagerClass 里添加 SkyDomeShaderClass 对象，并在渲染地形之前进行渲染（注意我们渲染的时候会关闭背面剔除和 Z-Buffer），部分渲染代码如下：

bool ZoneClass::Render(D3DClass* Direct3D, ShaderManagerClass* ShaderManager , TextureManagerClass* TextureManager)
{
	XMMATRIX worldMatrix, viewMatrix, projectionMatrix, baseViewMatrix, orthoMatrix;
	bool result;
	XMFLOAT3 cameraPosition;
	
	// Generate the view matrix based on the camera's position.
	m_Camera->Render();

	// Get the world, view, and projection matrices from the camera and d3d objects.
	Direct3D->GetWorldMatrix(worldMatrix);
	m_Camera->GetViewMatrix(viewMatrix);
	Direct3D->GetProjectionMatrix(projectionMatrix);
	m_Camera->GetBaseViewMatrix(baseViewMatrix);
	Direct3D->GetOrthoMatrix(orthoMatrix);
	
	// Get the position of the camera.
	cameraPosition = m_Camera->GetPosition();

	// Clear the buffers to begin the scene.
	Direct3D->BeginScene(0.0f, 0.0f, 0.0f, 1.0f);

	// Turn off back face culling and turn off the Z buffer.
	Direct3D->TurnOffCulling();
	Direct3D->TurnZBufferOff();

	// Translate the sky dome to be centered around the camera position.
	worldMatrix = XMMatrixTranslation(cameraPosition.x, cameraPosition.y, cameraPosition.z);

	// Render the sky dome using the sky dome shader.
	m_SkyDome->Render(Direct3D->GetDeviceContext());
	result = ShaderManager->RenderSkydomeShader(Direct3D->GetDeviceContext(), m_SkyDome->GetIndexCount(), worldMatrix, viewMatrix, 
						    projectionMatrix, m_SkyDome->GetApexColor(), m_SkyDome->GetCenterColor());
	if(!result)
	{
		return false;
	}

	// Reset the world matrix.
	Direct3D->GetWorldMatrix(worldMatrix);

	// Turn the Z buffer back and back face culling on.
	Direct3D->TurnZBufferOn();
	Direct3D->TurnOnCulling();

	if (m_wireFrame) {
		Direct3D->EnableWireframe();
	}

	// Render the terrain grid using the texture shader.
	m_Terrain->Render(Direct3D->GetDeviceContext());
	result = ShaderManager->RenderTerrainShader(Direct3D->GetDeviceContext(), m_Terrain->GetIndexCount(), worldMatrix, viewMatrix, 
						    projectionMatrix, TextureManager->GetTexture(0),  TextureManager->GetTexture(1), m_Light->GetDirection(), m_Light->GetDiffuseColor());
	if(!result)
	{
		return false;
	}

	if (m_wireFrame) {
		Direct3D->DisableWireframe();
	}

	// Render the user interface.
	if(m_displayUI)
	{
		result = m_UserInterface->Render(Direct3D, ShaderManager, worldMatrix, baseViewMatrix, orthoMatrix);
		if(!result)
		{
			return false;
		}
	}

	// Present the rendered scene to the screen.
	Direct3D->EndScene();

	return true;
}

  最终效果：

  源代码：DX11TerrainTutorial-SkyDomes