2D Pixel Shader没有效果？
我设置了一个基本的像素着色器（现在，其配置用于测试），但它似乎没有做任何事情。我这样设置：
uniform extern texture ScreenTexture;
const float bloomThreshhold = 0.4;
const float existingPixelColorMult = 1.1;
sampler ScreenS = sampler_state
{
Texture = <ScreenTexture>;
};
float4 BloomedColor(float2 texCoord: TEXCOORD0) : COLOR
{
// pick a pixel on the screen for this pixel, based on
// the calculated offset and direction
float2 temp = texCoord;
temp.x += 1;
float4 mainPixelColor = 0;
/*
float4 pixelPlus1X = tex2D(ScreenS, temp);
temp.x -= 2;
float4 pixelMinus1X = tex2D(ScreenS, temp);
temp.x += 1;
temp.y += 1;
float4 pixelPlus1Y = tex2D(ScreenS, temp);
temp.y -= 2;
float4 pixelMinus1Y = tex2D(ScreenS, temp);
*/
return mainPixelColor;
}
technique Bloom
{
pass P0
{
PixelShader = compile ps_1_1 BloomedColor();
}
}
加载代码如下：
glowEffect = Content.Load<Effect>("GlowShader");
glowEffect.CurrentTechnique = glowEffect.Techniques[0];
并且使用代码是：
spriteBatch.Begin();
glowEffect.Begin();
glowEffect.CurrentTechnique.Passes[0].Begin();
spriteBatch.Draw(screenImage, Vector2.Zero, Color.White);
spriteBatch.End();
glowEffect.CurrentTechnique.Passes[0].End();
glowEffect.End();
加载似乎工作正常，并且当我使用该方法渲染纹理时没有抛出错误，但它的作用就像效果代码不是一样在那里。不可能是我使用了错误版本的着色器（我用2.0和1.1版本进行了测试），那为什么呢？ （使用XNA 3.1）
I set up a basic pixel shader (right now, its configured for testing), and it doesn't seem to do anything. I set it up like so:
uniform extern texture ScreenTexture;
const float bloomThreshhold = 0.4;
const float existingPixelColorMult = 1.1;
sampler ScreenS = sampler_state
{
Texture = <ScreenTexture>;
};
float4 BloomedColor(float2 texCoord: TEXCOORD0) : COLOR
{
// pick a pixel on the screen for this pixel, based on
// the calculated offset and direction
float2 temp = texCoord;
temp.x += 1;
float4 mainPixelColor = 0;
/*
float4 pixelPlus1X = tex2D(ScreenS, temp);
temp.x -= 2;
float4 pixelMinus1X = tex2D(ScreenS, temp);
temp.x += 1;
temp.y += 1;
float4 pixelPlus1Y = tex2D(ScreenS, temp);
temp.y -= 2;
float4 pixelMinus1Y = tex2D(ScreenS, temp);
*/
return mainPixelColor;
}
technique Bloom
{
pass P0
{
PixelShader = compile ps_1_1 BloomedColor();
}
}
with the loading code like:
glowEffect = Content.Load<Effect>("GlowShader");
glowEffect.CurrentTechnique = glowEffect.Techniques[0];
and use code is:
spriteBatch.Begin();
glowEffect.Begin();
glowEffect.CurrentTechnique.Passes[0].Begin();
spriteBatch.Draw(screenImage, Vector2.Zero, Color.White);
spriteBatch.End();
glowEffect.CurrentTechnique.Passes[0].End();
glowEffect.End();
Loading seems to work fine, and there are no errors thrown when I use that method to render the texture, but it acts like the effect code isn't in there. It can't be that I'm using the wrong version of shaders (I tested with 2.0 and 1.1 versions), so why? (Using XNA 3.1)
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评论（2）
您将为每个像素返回 0。您已注释掉任何会返回与 0 不同的值的代码。0 是黑色，如果您正在进行任何类型的渲染，您要么得到黑色（如果混合模式将其显示为颜色），要么没有变化（如果混合模式将结果相乘）。当然，您可以尝试使用奇怪的颜色（如果您只是尝试查看着色器是否正在加载和操作）。霓虹绿有人吗？然后，一旦确认至少正在处理它，就开始取消对该代码的注释并评估结果。
最后，如果 Bloom 是您所追求的，Microsoft 有一个非常有用的示例，您可能会从这里学到很多东西：
http://create.msdn.com/en-US/education/catalog/sample/bloom
You're returning 0 for every pixel. You have commented out any code that would return a different value than 0. 0 is black and if you're doing any sort of render you'll either get black (if the blend mode shows this as a color) or no change (if the blend mode multiplies the result). You can of course (if you were just attempting to see if the shader is being loaded and operated) try using an oddball color. Neon green anyone? Then, once you confirm it is being at least processed, start uncommenting that code and assessing the result.
Finally, if Bloom is what you're after, Microsoft has a very useful sample you will probably learn a lot from here:
http://create.msdn.com/en-US/education/catalog/sample/bloom
如果您使用的是 XNA 4.0，请参阅 肖恩·哈格里夫斯对此有何评论。
If you're using XNA 4.0, see what Shawn Hargreaves has to say about this.