前言
在shadertoy里编写各种效果的时候，最开始经常会需要把800*450的矩形屏幕空间映射到正方形屏幕空间中。这篇文章记录一下这个过程。
效果和代码
矩形屏幕空间的效果
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
// Normalized pixel coordinates (from 0 to 1)
vec2 uv = fragCoord/iResolution.xy;
// Output to screen
fragColor = vec4(uv,0.,1.0);
}
正方形屏幕空间的效果
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
// Normalized pixel coordinates (from 0 to 1)
vec2 uv = fragCoord/iResolution.xy;
uv.x *= iResolution.x / iResolution.y;
// Output to screen
fragColor = vec4(uv,0.,1.0);
}
把uv坐标原点移到屏幕中间
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
// Normalized pixel coordinates (from 0 to 1)
vec2 uv = fragCoord/iResolution.xy;
uv -= .5;
uv.x *= iResolution.x / iResolution.y;
// Output to screen
fragColor = vec4(uv,0.,1.0);
}
