13.Shader

终于到了Shader部分，不过书中只有vertex shader和pixel shader，呃。而且书中是以CG为例子的，不过都差不多。

写Shader需要在.material中先定义shader。

fragment_program MyFragmentShader1 cg
{
	source Ogre3DBeginnersGuideShaders.cg
	entry_point MyFragmentShader1
	profiles ps_1_1 arbfp1
}

vertex_program MyVertexShader1 cg
{
	source Ogre3DBeginnersGuideShaders.cg
	entry_point MyVertexShader1
	profiles vs_1_1 arbvp1

	default_params
	{
		param_named_auto worldViewMatrix worldviewproj_matrix
	}
}

material MyMaterial13
{
	technique
	{
		pass
		{
			vertex_program_ref MyVertexShader1
			{
			}
			fragment_program_ref MyFragmentShader1
			{
			}
		}
	}
}

然后要再创建一个.cg文件，写入shader函数。

void MyVertexShader1(float4 position : POSITION,
				out float4 oPosition : POSITION,
				uniform float4x4 worldViewMatrix)
{
	oPosition = mul(worldViewMatrix, position);
}

void MyFragmentShader1(out float4 color : COLOR)
{
	color = float4(1, 0, 1, 0);
}

大概的格式与步骤就是这样了，要是用就直接使用这个材质。

下面再贴一个复杂一点的，使用了纹理，并且实时改变了顶点位置。

fragment_program MyFragmentShader2 cg
{
	source Ogre3DBeginnersGuideShaders.cg
	entry_point MyFragmentShader2
	profiles ps_1_1 arbfp1
}

vertex_program MyVertexShader5 cg
{
	source Ogre3DBeginnersGuideShaders.cg
	entry_point MyVertexShader5
	profiles vs_1_1 arbvp1

	default_params
	{
		param_named_auto worldViewMatrix worldviewproj_matrix
		param_named_auto pulseTime time
	}
}

material MyMaterial17
{
	technique
	{
		pass
		{
			vertex_program_ref MyVertexShader5
			{
			}
			fragment_program_ref MyFragmentShader2
			{
			}
			texture_unit
			{
				texture terr_rock6.jpg
			}
		}
	}
}

对应的CG文件

void MyFragmentShader2(float2 uv : TEXCOORD0,
				out float4 color : COLOR,
				uniform sampler2D texture)
{
	color = tex2D(texture, uv);
}

void MyVertexShader5(uniform float pulseTime,
			float4 position : POSITION,
			out float4 oPosition : POSITION,
			float2 uv : TEXCOORD0,
			out float2 oUv : TEXCOORD0,
			uniform float4x4 worldViewMatrix)
{
	oPosition = mul(worldViewMatrix, position);
	oPosition.x *= (2 + sin(pulseTime));
	oUv = uv;
}