问题描述
我目前正在学习有关在GLSL中生成噪声模式的信息。
我正在尝试使用GLSL中的片段着色器创建矩形,颜色和噪点的组合。这是我当前的代码:
#ifdef GL_ES
precision mediump float;
#endif
uniform vec2 u_resolution;
uniform vec2 u_mouse;
// 2D Random
float random (in vec2 st) {
return fract(sin(dot(st.xy,vec2(12.9898,79)))
* 43758.5453123);
}
float noise (in vec2 st)
{
vec2 i = floor(st + 1.0);
vec2 f = fract(st);
// Four corners in 2D of a tile
float a = random(i);
float b = random(i + vec2(1.0,0.0));
float c = random(i + vec2(0.0,1.0));
float d = random(i + vec2(1.0,1.0));
vec2 u = f*f*(3.0-2.0*f);
u = smoothstep(0.6,1.0,f);
// Mix 4 coorners percentages
return mix(a,b,u.x) +
(c - a)* u.y * (1.0 - u.x) +
(d - b) * u.x * u.y;
}
void main() {
vec2 st = gl_FragCoord.xy/u_resolution.xy;
vec3 color = vec3(0.423,0.459,1.000);
vec2 pos = vec2(st * 4.0);
// Use the noise function
float n = noise(pos);
gl_FragColor = vec4(vec3(n),color);
}
目前我能生成的只是黑白正方形和矩形,无论我如何调整“ vec3颜色”变量,我都无法使其显示各种颜色的矩形。
我的问题是:如何调整代码,使其分解为少数几个矩形,而不是正方形和矩形?如何使颜色适用于这些矩形?这对我来说仍然是陌生的,因此不胜感激。
解决方法
如何使颜色适用于这些矩形
您必须将color
乘以梯度n
:
gl_FragColor = vec4(color * n,1.0);
矩形的错位与直线有关
u = smoothstep(0.6,1.0,f)
您必须根据平滑区域的大小移动矩形:
float noise (in vec2 st)
{
float smoothsize = 0.2;
st -= smoothsize;
vec2 i = floor(st + 1.0);
vec2 f = fract(st);
// [...]
vec2 u = f*f*(3.0-2.0*f);
u = smoothstep(1.0- 2.0*smoothsize,f);
// [...]
}
如果要生成正方形而不是矩形,则必须按纵横比缩放st.x
:
vec2 st = gl_FragCoord.xy/u_resolution.xy;
st.x *= u_resolution.x/u_resolution.y;
完整的片段着色器:
#ifdef GL_ES
precision mediump float;
#endif
uniform vec2 u_resolution;
uniform vec2 u_mouse;
// 2D Random
float random (in vec2 st)
{
return fract(sin(dot(st.xy,vec2(12.9898,79))) * 43758.5453123);
}
float noise (in vec2 st)
{
float smoothsize = 0.2;
st -= smoothsize;
vec2 i = floor(st + 1.0);
vec2 f = fract(st);
// Four corners in 2D of a tile
float a = random(i);
float b = random(i + vec2(1.0,0.0));
float c = random(i + vec2(0.0,1.0));
float d = random(i + vec2(1.0,1.0));
vec2 u = f*f*(3.0-2.0*f);
u = smoothstep(1.0- 2.0*smoothsize,f);
// Mix 4 corners percentages
return mix(a,b,u.x) + (c-a) * u.y * (1.0-u.x) + (d-b) * u.x * u.y;
}
void main() {
vec2 st = gl_FragCoord.xy/u_resolution.xy;
// st.x *= u_resolution.x/u_resolution.y; <--- optional
// Use the noise function
float n = noise(st * 4.0);
vec3 color = vec3(0.423,0.459,1.000);
gl_FragColor = vec4(color * n,1.0);
}