Question

我需要用距离场方法放大RGBA图像。我有代码计算灰度图片的距离变换。我如何使用它与32位图片？实际上如何放大图片？

我有用于放大灰度图片的着色器，这里是：

precision highp float;



uniform sampler2D u_Texture;    // The input texture.
uniform sampler2D u_DistTexture;    // The input texture.

varying vec2 v_TexCoordinate;   // Interpolated texture coordinate per fragment.

const float _128_DIV_255 = 0.50196;
const float DF_SIZE = 16.0;

void postDF()
{
    float D = DF_SIZE * (texture2D(u_DistTexture, v_TexCoordinate).r - _128_DIV_255);
    float aastep = length(vec2(dFdx(D), dFdy(D)));
    //float aastep = DF_SIZE/2.0;
    float pattern = smoothstep(-aastep, aastep, D);


    if(D >= 0.0)
    {
        vec4 texColor;
        float d_step = D / (DF_SIZE / 2.0);
        if (d_step < 0.125)
            texColor = texture2D(u_Texture, v_TexCoordinate);
        else
            texColor = vec4(pattern);

        gl_FragColor = mix(texColor, vec4(pattern), pattern);
    }
    else
        gl_FragColor = vec4(vec3(0.0), 1.0);

}


// The entry point for our fragment shader.
void main()
{
    if(v_TexCoordinate.x > 0.5)
    {
    gl_FragColor = texture2D(u_Texture, v_TexCoordinate);
    }
    else
    {
        //gl_FragColor = texture2D(u_DistTexture, v_TexCoordinate);
    postDF();
    }

uniform sampler2D u_Texture; // The input texture. uniform sampler2D u_DistTexture; // The input texture. varying vec2 v_TexCoordinate; // Interpolated texture coordinate per fragment. const float _128_DIV_255 = 0.50196; const float DF_SIZE = 16.0; void postDF() { float D = DF_SIZE * (texture2D(u_DistTexture, v_TexCoordinate).r - _128_DIV_255); float aastep = length(vec2(dFdx(D), dFdy(D))); //float aastep = DF_SIZE/2.0; float pattern = smoothstep(-aastep, aastep, D); if(D >= 0.0) { vec4 texColor; float d_step = D / (DF_SIZE / 2.0); if (d_step < 0.125) texColor = texture2D(u_Texture, v_TexCoordinate); else texColor = vec4(pattern); gl_FragColor = mix(texColor, vec4(pattern), pattern); } else gl_FragColor = vec4(vec3(0.0), 1.0); } // The entry point for our fragment shader. void main() { if(v_TexCoordinate.x > 0.5) { gl_FragColor = texture2D(u_Texture, v_TexCoordinate); } else { //gl_FragColor = texture2D(u_DistTexture, v_TexCoordinate); postDF(); }

u_Texture是灰度图像，u_DistTexture是它的距离场。我可以写类似的东西，但是对于RGBA图像吗？

彩色图像的距离变换

0 个答案: