Question

我需要在这个顶点着色器/碎片整理器中从简单的灰度深度更改为RGBA编码的深度，特别是要显示ChromaDepth（tm） - color-scheme而不是灰度？ http://www.chromatek.com/pix/101color.jpg

<script id="vert" type="webgl/fragment-shader">
    uniform float near;
    uniform float far;
    varying vec3 color;

    void main() {
        gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
        float depth = 1.0 - ((gl_Position.z - near) / (far - near));
        color = vec3(depth);
    }  
</script>
<script id="frag" type="webgl/fragment-shader">
    varying vec3 color;

    void main() {
        gl_FragColor = vec4(color, 1.0);
    }
</script>

Answer 1

您正在输出行color = vec3(depth)中的颜色。函数vec3的这种变体创建了一个向量，其中所有3个部分都等于输入值。您也可以使用它来创建一个由3部分组成的向量：color = vec3(red, geen, blue)。如果您还想将Alpha值传递给片段着色器，则必须将其更改为vec4（红色，绿色，蓝色，alpha），并将varying vec3 color的声明更改为varying vec4 color in顶点和片段着色器。

ChromaDepth用于从深度计算正确的红色，绿色和蓝色值的算法已发布here。这是相关部分：

//Definition of 3d_red component of the color. The value show be between 1
//and 0 over the Range of 0 to 0.75. It should be 0 for all Ranges greater
//than 0.75. From 0 to 0.75 it is calculated by Red_func.
define Red_Range Range/0.9
define Red_func 
(-2.13*Red_Range^4-1.07*Red_Range^3+0.133*Red_Range^2+0.0667*Red_Range+1)
define Cc (Red_func <0 || Red_Range>0.75 ? 0:1)
define Dd (Red_func >1 ? 1:0)
define 3d_red (Red_Range<0.75 ? Red_func:Cc*Dd)

//Definition of 3d_green component of the color. The value should be between
//0 and 1 over the Range of 0 to 1, starting from 0, rising to 1, then falling
//to 0 again. It should be 0 at both extremes of Range.
define Green_func1 (1.6*Range^2+1.2*Range)
define Green_func2 (3.2*Range^2-6.8*Range+3.6)
define 3d_green (Range<=0.5 ? Green_func1:Green_func2)

//Definition of 3d_blue component of the color. The value should rise from
//0 at a Range of 0.5 up to 1 at a Range of 1. Below Range 0.5 the value
//must be 0.
define Blue_func (-4.8*Range^2+9.2*Range-3.4)
define 3d_blue (Range>0.5 ? Blue_func:0)

这些函数的输入值是“Range”，你在代码中称之为“深度”（0.0是最接近的，1.0是最远的）。

Answer 2

谢谢Philipp。这是我的实施：

<script id="vert" type="webgl/fragment-shader">
        uniform float near;
        uniform float far;
        varying vec3 color; 

        float func_r(float r_range)
        {  
          float r_depth = (-2.13*r_range*r_range*r_range*r_range-1.07*r_range*r_range*r_range+0.133*r_range*r_range+0.0667*r_range+1.0);
            return r_depth;
        }

        float func_g1 (float g_range)
        {
          float g_depth = (1.6*g_range*g_range+1.2*g_range);
          return g_depth;
        }

        float func_g2 (float g_range2)
        {
          float g_depth2 = (3.2*g_range2*g_range2-6.8*g_range2+3.6);
          return g_depth2;
        }

        float func_b (float b_range)
        {
          float b_depth = (-4.8*b_range*b_range+9.2*b_range-3.4);
          return b_depth;
        }

        void main() {
            gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
            float depth = 0.0 + ((gl_Position.z - near) / (far - near));

            /* ### Definition of 3d_red component of the color.*/
            float Red_Range = depth / 0.9;
            float Cc = (func_r(Red_Range) < 0.0 || Red_Range > 0.75 ? 0.0:1.0);
            float Dd = (func_r(Red_Range) > 1.0 ? 1.0:0.0);  
            float calc_r = (Red_Range < 0.75 ? func_r(Red_Range) : Cc*Dd); 

            /* ### Definition of 3d_green component of the color.*/            
            float calc_g = (depth <= 0.5 ? func_g1(depth) : func_g2(depth));

            /* ### Definition of 3d_blue component of the color.*/                      
            float calc_b = (depth > 0.5 ? func_b(depth) : 0.0);

            color = vec3(calc_r,calc_g,calc_b);
        }  
    </script>
    <script id="frag" type="webgl/fragment-shader">
        varying vec3 color;

        void main() {
            gl_FragColor = vec4(color, 1.0);
        }
    </script>

自定义深度着色器从灰度到RGBA

2 个答案: