Question

我为Monogame项目编写了HLSL着色器，该着色器使用环境照明来创建昼/夜循环。

#if OPENGL
    #define SV_POSITION POSITION
    #define VS_SHADERMODEL vs_3_0
    #define PS_SHADERMODEL ps_3_0
#else
    #define VS_SHADERMODEL vs_4_0_level_9_1
    #define PS_SHADERMODEL ps_4_0_level_9_1
#endif

sampler s0;

struct VertexShaderOutput
{
    float4 Position : SV_POSITION;
    float4 Color : COLOR0;
    float2 TextureCoordinates : TEXCOORD0;
};


float ambient = 1.0f;
float percentThroughDay = 0.0f;

float4 MainPS(VertexShaderOutput input) : COLOR
{
    float4 pixelColor = tex2D(s0, input.TextureCoordinates);
    float4 outputColor = pixelColor;

    // lighting intensity is gradient of pixel position
    float Intensity = 1 + (1  - input.TextureCoordinates.y) * 1.3;
    outputColor.r = outputColor.r / ambient * Intensity;
    outputColor.g = outputColor.g / ambient * Intensity;
    outputColor.b = outputColor.b / ambient * Intensity;

    // sun set/rise blending 
    float exposeRed = (1 + (.39 - input.TextureCoordinates.y) * 8); // overexpose red
    float exposeGreen = (1 + (.39 - input.TextureCoordinates.y) * 2); // some extra green for the blue pixels
    float exposeBlue = (1 + (.39 - input.TextureCoordinates.y) * 6); // some extra blue 

    // happens over full screen
    if (input.TextureCoordinates.y < 1.0f) {

        float redAdder = max(1, (exposeRed * (percentThroughDay/0.25f))); // be at full exposure at 25% of day gone
        float greenAdder = max(1, (exposeGreen * (percentThroughDay/0.25f))); // be at full exposure at 25% of day gone
        float blueAdder = max(1, (exposeBlue * (percentThroughDay/0.25f))); // be at full exposure at 25% of day gone

        // begin reducing adders
        if (percentThroughDay >= 0.25f && percentThroughDay < 0.50f) {
            redAdder = max(1, (exposeRed * (1-(percentThroughDay - 0.25f)/0.25f)));
            greenAdder = max(1, (exposeGreen * (1-(percentThroughDay - 0.25f)/0.25f)));
            blueAdder = max(1, (exposeGreen * (1-(percentThroughDay - 0.25f)/0.25f)));
        }

        //mid day
        else if (percentThroughDay >= 0.50f && percentThroughDay < 0.75f) {
            redAdder = 1;
            greenAdder = 1;
            blueAdder = 1;
        }

        // add adders back for sunset
        else if (percentThroughDay >= 0.75f && percentThroughDay < 0.85f) {
            redAdder = max(1, (exposeRed * ((percentThroughDay - 0.75f)/0.10f)));
            greenAdder = max(1, (exposeGreen * ((percentThroughDay - 0.75f)/0.10f)));
            blueAdder = max(1, (exposeBlue * ((percentThroughDay - 0.75f)/0.10f)));
        }

        // begin reducing adders
        else if (percentThroughDay >= 0.85f) {
            redAdder = max(1, (exposeRed * (1-(percentThroughDay - 0.85f)/0.15f)));
            greenAdder = max(1, (exposeGreen * (1-(percentThroughDay - 0.85f)/0.15f)));
            blueAdder = max(1, (exposeBlue * (1-(percentThroughDay - 0.85f)/0.15f)));
        }

        outputColor.r = outputColor.r * redAdder;
        outputColor.g = outputColor.g * greenAdder;
        outputColor.b = outputColor.b * blueAdder;
    }

    return outputColor;
}

technique ambientLightDayNight
{
    pass P0
    {
        PixelShader = compile ps_2_0 MainPS();
    }
};

这在大多数情况下都是我想要的（尽管它肯定可以使用一些计算优化）。

但是，我现在正在考虑在游戏中添加聚光灯供玩家使用。我跟随着this method一起工作，该工作独立于environmentLight着色器。这是一个使用lightMask的非常简单的着色器。

sampler s0;  

texture lightMask;  
sampler lightSampler = sampler_state{Texture = lightMask;};  

float4 PixelShaderLight(float2 coords: TEXCOORD0) : COLOR0  
{  
    float4 color = tex2D(s0, coords);  
    float4 lightColor = tex2D(lightSampler, coords);  
    return color * lightColor;  
}  


technique Technique1  
{  
    pass Pass1  
    {  
        PixelShader = compile ps_2_0 PixelShaderLight();  
    }  
}

我的问题是现在同时使用这两个着色器。我当前的方法是将游戏场景绘制到渲染目标，应用环境光着色器，然后通过绘制游戏场景（使用应用聚光灯着色器时，将其添加到客户端屏幕。

这带来了多个问题：

在环境光完全使光源周围的所有物体变黑之后应用聚光灯着色器，而实际上，光源周围的区域应该是环境光。
在“夜间”时，聚光灯着色器中计算的光强度（光的亮度）太暗了，因为它是根据环境光着色器的输出来计算灯光颜色的。

我曾尝试在聚光灯着色器之后应用环境光着色器，但这只会使大部分内容呈现黑色，因为环境光是根据黑色背景计算的。

我尝试将一些代码添加到聚光灯着色器中，以将黑色像素着色为白色，以显示环境光背景，但是仍然针对较暗的环境光计算光强度-导致非常暗淡的光。

另一种想法是仅修改我的环境光着色器以将lightMask作为参数，而不只是将环境光应用于在光罩上标记的光。然后，我可以只使用聚光灯着色器来应用灯光的外观并修改颜色。但是我不确定是否应该将这两个看似独立的灯光效果塞入一个像素着色器中。当我尝试此操作时，我的着色器也没有编译，因为算术操作太多。

所以我对每个人的问题是：

我应该避免将多种效果塞入一个像素着色器吗？
通常，我如何将聚光灯应用于可能是“黑暗”的环境光效果？

编辑

我的解决方案-最终没有使用聚光灯着色器，而是仍然按照文章中给出的纹理绘制光罩，然后将该光罩传递到此环境光着色器并抵消纹理渐变。

float4 MainPS(VertexShaderOutput input) : COLOR
{

    float4 constant = 1.5f;
    float4 pixelColor = tex2D(s0, input.TextureCoordinates);
    float4 outputColor = pixelColor;

    // lighting intensity is gradient of pixel position
    float Intensity = 1 + (1  - input.TextureCoordinates.y) * 1.05;
    outputColor.r = outputColor.r / ambient * Intensity;
    outputColor.g = outputColor.g / ambient * Intensity;
    outputColor.b = outputColor.b / ambient * Intensity;

    // sun set/rise blending  
    float gval = (1 - input.TextureCoordinates.y); // replace 1 with .39 to lock to 39 percent of screen (this is how it was before)
    float exposeRed = (1 + gval * 8); // overexpose red
    float exposeGreen = (1 + gval * 2); // some extra green
    float exposeBlue = (1 + gval * 4); // some extra blue 

    float quarterDayPercent = (percentThroughDay/0.25f);
    float redAdder = max(1, (exposeRed * quarterDayPercent)); // be at full exposure at 25% of day gone
    float greenAdder = max(1, (exposeGreen * quarterDayPercent)); // be at full exposure at 25% of day gone
    float blueAdder = max(1, (exposeBlue * quarterDayPercent)); // be at full exposure at 25% of day gone

    // begin reducing adders
    if (percentThroughDay >= 0.25f ) {
        float gradientVal1 = (1-(percentThroughDay - 0.25f)/0.25f);
        redAdder = max(1, (exposeRed * gradientVal1));
        greenAdder = max(1, (exposeGreen * gradientVal1));
        blueAdder = max(1, (exposeGreen * gradientVal1));
    }

    //mid day
    if (percentThroughDay >= 0.50f) {
        redAdder = 1;
        greenAdder = 1;
        blueAdder = 1;
    }

    // add adders back for sunset
    if (percentThroughDay >= 0.75f) {
        float gradientVal2 = ((percentThroughDay - 0.75f)/0.10f);
        redAdder = max(1, (exposeRed * gradientVal2));
        greenAdder = max(1, (exposeGreen * gradientVal2));
        blueAdder = max(1, (exposeBlue * gradientVal2));
    }

    // begin reducing adders
    if (percentThroughDay >= 0.85f) {

        float gradientVal3 = (1-(percentThroughDay - 0.85f)/0.15f);
        redAdder = max(1, (exposeRed * gradientVal3));
        greenAdder = max(1, (exposeGreen * gradientVal3));
        blueAdder = max(1, (exposeBlue * gradientVal3));
    }

    outputColor.r = outputColor.r * redAdder;
    outputColor.g = outputColor.g * greenAdder;
    outputColor.b = outputColor.b * blueAdder;

    // first check if we are in a lightMask light
    float4 lightMaskColor = tex2D(lightSampler, input.TextureCoordinates);
    if (lightMaskColor.r != 0.0f || lightMaskColor.g != 0.0f || lightMaskColor.b != 0.0f) 
    {
        // we are in the light so don't apply ambient light
        return pixelColor * (lightMaskColor + outputColor) * constant; // have to offset by outputColor here because the lightMask is pure black
    }

    return outputColor * pixelColor * constant; // must multiply by pixelColor here to offset the lightMask bounds. TODO: could try to restore original color by removing this multiplaction and factoring in more of an offset on ln 91
}

Answer 1

要根据需要链接灯，您需要使用其他方法。正如您已经遇到的那样，仅在颜色上链接灯将不起作用，因为一旦颜色变为黑色，就无法再突出显示。要处理多个灯光，有两种典型的方法：前向阴影和延迟阴影。每种方法都有其优点和缺点，因此您需要查看最适合您情况的外观。

前向阴影

此方法是您测试过的一种方法，可将所有照明计算填充到一个阴影通道中。您将所有光强度加在一起成为最终的光强度，然后将其乘以颜色。

优点是性能和简单性，缺点是灯光数量和更复杂的着色器代码的限制。

延迟着色

此方法将单个灯光彼此分离，可用于绘制具有很多灯光的场景。每个光源都需要原始的场景颜色（反照率）来计算其最终图像的一部分。因此，您首先要在没有任何光照的情况下渲染场景（通常称为颜色缓冲区或反照率缓冲区）。然后，可以通过将其与反照率相乘并将其添加到最终图像中来分别渲染每个光。因此，即使在较暗的部分，原始颜色也会再次变亮。

优点是清洁的结构，即使形状不同，也可以使用很多灯。缺点是必须进行的额外缓冲区和绘制调用。

在黑暗的环境光上应用聚光灯-HLSL-Monogame

1 个答案: