GLSL自定义/不对具有顶点颜色的三角形进行插值 [英] GLSL custom/no interpolation of triangles with vertex colors

问题描述

我要实现的效果是具有清晰轮廓的顶点颜色.因此，在三角形内部，片段着色器应使用最接近该片段的任何顶点的颜色.

The effect I want to achieve is vertex color with sharp contours. So inside the triangle the fragment shader should use the color of whatever vertex is closest to that fragment.

现在考虑这个问题时，我能想到的唯一解决方案是将tex坐标1,0,0 0,1,0和0,0,1分配给这三个顶点，并具有2个(重新排序的)顶点顶点颜色阵列，然后从其对应的tex坐标最高的颜色中选择.此方法将至少为每个顶点添加9个以上的浮点数.由于我的网格物体经常退出，这会减慢应用程序的速度，并显着增加内存占用.

Now when thinking about it, the only solution I can come up with is assigning tex coords 1,0,0 0,1,0 and 0,0,1 to the three vertices and have 2 (reoordered) duplicates of the vertex color array and then choose from the color aray of which the corresponding tex coord is highest. This method would at least add 9 more floats to each vertex. Which will slow down the application as my meshes are changing quit often and increase the memory footprint significantly.

是否有更好/更简便的方法来实现这一目标?

Is there a better/easier way to achieve this?

推荐答案

[替换了不正确的原始图片]

这应该实际上有效...

//vert
out vec3 colour;
...

//geom
//simple passthrough but dupe colours to separate and include barycentric coord
layout(triangles) in;
layout(triangle_strip, max_vertices = 3) out;
in vec3 colour[];
flat out vec3 colours[3];
out vec3 coord;
...
for (int i = 0; i < 3; ++i)
    colours[i] = colour[i];
for (int i = 0; i < 3; ++i)
{
    coord = vec3(0.0);
    coord[i] = 1.0;
    gl_Position = gl_in[i].gl_Position;
    EmitVertex();
}

//frag
flat in vec3 colours[3]; //triangle's 3 vertex colours
in vec3 coord; //barycentric weights as a result of interp
...
//get index of biggest coord
int i = (coord.x > cood.y && coord.x > coord.z) ? 0 :
    ((coord.y > coord.z) ? 1 : 2);
//choose that colour
vec3 fragColour = colours[i];

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