调试 chroma key shader 不成，求助~

Cocos2d-x
#1

这是从 obs studio 里取来的shader代码，稍作了修改，d3d9下调试的。
shader 能顺利编译运行。
本来想抠蓝色，结果抠掉的是红色。
找不出缘由，希望大家帮助下。

调试不需要编译obs，只需把shader代码用到自己d3d9程序里即可。

记得初始化 contrast, brightness,gamma 等变量。

变量初始化的c代码（很简洁）：
github.com/jp9000/obs-studio/blob/31f106c1b533c8b2e1a15ad914fb9d794277bcb6/plugins/obs-filters/chroma-key-filter.c

shader 代码如下：

uniform float4x4 ViewProj;
uniform texture image;

uniform float4x4 yuv_mat = { 0.182586,  0.614231,  0.062007, 0.062745,
                            -0.100644, -0.338572,  0.439216, 0.501961,
                             0.439216, -0.398942, -0.040274, 0.501961,
                             0.000000,  0.000000,  0.000000, 1.000000};

uniform float4 color;
uniform float contrast;
uniform float brightness;
uniform float gamma;

uniform float2 chroma_key;
uniform float2 pixel_size;
uniform float similarity;
uniform float smoothness;
uniform float spill;

sampler textureSampler = 
sampler_state 
{ 
	Texture = <image>;
	MinFilter = Linear;
	MagFilter = Linear;
	AddressU = Clamp;
	AddressV = Clamp;
};

struct VertData {
	float4 pos : POSITION;
	float2 uv  : TEXCOORD;
};

VertData VSDefault(VertData v_in)
{
	VertData vert_out;
	vert_out.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
	vert_out.uv  = v_in.uv;
	return vert_out;
}

float4 CalcColor(float4 rgba)
{
	return float4(pow(rgba.rgb, float3(gamma, gamma, gamma)) * contrast + brightness, rgba.a);
}

float GetChromaDist(float3 rgb)
{
	float4 yuvx = mul(float4(rgb.rgb, 1.0), yuv_mat);
	return distance(chroma_key, yuvx.yz);
}

float4 SampleTexture(float2 uv)
{
	return tex2D(textureSampler, uv);
}

float GetBoxFilteredChromaDist(float3 rgb, float2 texCoord)
{
	float distVal = GetChromaDist(rgb);
	distVal += GetChromaDist(SampleTexture(texCoord-pixel_size).rgb);
	distVal += GetChromaDist(SampleTexture(texCoord-float2(pixel_size.x, 0.0)).rgb);
	distVal += GetChromaDist(SampleTexture(texCoord-float2(pixel_size.x, -pixel_size.y)).rgb);

	distVal += GetChromaDist(SampleTexture(texCoord-float2(0.0, pixel_size.y)).rgb);
	distVal += GetChromaDist(SampleTexture(texCoord+float2(0.0, pixel_size.y)).rgb);

	distVal += GetChromaDist(SampleTexture(texCoord+float2(pixel_size.x, -pixel_size.y)).rgb);
	distVal += GetChromaDist(SampleTexture(texCoord+float2(pixel_size.x, 0.0)).rgb);
	distVal += GetChromaDist(SampleTexture(texCoord+pixel_size).rgb);
	return distVal / 9.0;
}

float4 ProcessChromaKey(float4 rgba, VertData v_in)
{
	float chromaDist = GetBoxFilteredChromaDist(rgba.rgb, v_in.uv);
	float baseMask = chromaDist - similarity;
	float fullMask = pow(saturate(baseMask / smoothness), 1.5);
	float spillVal = pow(saturate(baseMask / spill), 1.5);

	rgba.a *= fullMask;

	float desat = (rgba.r * 0.2126 + rgba.g * 0.7152 + rgba.b * 0.0722);
	rgba.rgb = saturate(float3(desat, desat, desat)) * (1.0 - spillVal) + rgba.rgb * spillVal;

	return CalcColor(rgba);
}

float4 PSChromaKeyRGBA(VertData v_in) : SV_TARGET
{
	float4 rgba = tex2D(textureSampler, v_in.uv) * color;
	return ProcessChromaKey(rgba, v_in);
	//return float4( 1.0f, 0.0f, 0.0f, 0.5f );
	//return rgba;
}

technique Draw
{
	pass p0
	{
		SetVertexShader(CompileShader(vs_3_0,VSDefault()));
		SetPixelShader(CompileShader(ps_3_0,PSChromaKeyRGBA()));
	}
}