GLSL 多纹理 - 混合纹理

Posted 2023-02-16

【中文标题】GLSL 多纹理 - 混合纹理

【英文标题】：GLSL multi-texturing- blending textures

【发布时间】：2016-09-29 20:57:33

【问题描述】：

我正在尝试在 OpenGL 中实现多纹理。使用的纹理基于给定顶点的表面法线 - 垂直度越高，第二个纹理的可见度就越多。

Here 是我目前所拥有的。

我现在想将边缘融合在一起，而不是拥有那种硬边缘。是否可以以这种方式混合纹理？如果是这样，我该怎么做？

这是我的片段着色器代码：

#version 150

in vec2 pass_textureCoords;
in vec3 surfaceNormal;
in vec3 toLightVector;
in vec3 toCamera;
in vec3 playerPosition;
in vec4 vertexPosition;

in float blendPosition;
in float visibility;

out vec4 out_Color;

uniform sampler2D texture0;
uniform sampler2D texture1;

uniform vec3 skyColour;
uniform vec3 light_colour;
uniform float shineDamper;
uniform float reflectivity;

void main(void)
  vec3 unitNormal = normalize(surfaceNormal);
  vec3 unitLightVector = normalize(toLightVector);

  float nDot1 = dot(unitNormal,unitLightVector);
  float brightness = max(nDot1,0.2);
  vec3 diffuse = brightness * light_colour;

  vec3 unitToCamera = normalize(toCamera);
  vec3 lightDirection = -unitLightVector;
  vec3 reflectedLightDirection = reflect(lightDirection,unitNormal);

  float specular = dot(reflectedLightDirection, unitToCamera);
  specular = max(specular,0.0);
  float damped = pow(specular,shineDamper);
  vec3 finalSpecular = damped * reflectivity * light_colour;

  out_Color = (vec4(diffuse,1.0) * texture(texture0,pass_textureCoords)) + vec4(-20,-20,0.0,0.0);
  out_Color = (vec4(diffuse,1.0) * texture(texture0,pass_textureCoords));
  out_Color = mix(vec4(skyColour,1.0),out_Color,visibility);

  if(vertexPosition.y < -6.1 || surfaceNormal.y < 0.6)
    out_Color = (vec4(diffuse,1.0) * texture(texture1,pass_textureCoords)) + vec4(-20,-20,0.0,0.0);
    out_Color = (vec4(diffuse,1.0) * texture(texture1,pass_textureCoords));
    out_Color = mix(vec4(diffuse,1.0) * texture(texture0,pass_textureCoords),out_Color,1);
    out_Color = mix(vec4(skyColour,1.0),out_Color,visibility);
  
  if(playerPosition.y < -6.1)
    out_Color = mix(vec4(0.0,0.3,0.5,1.0),out_Color,0.1);
  

编辑：

这是任何感兴趣的人的新片段着色器代码

更新片段着色器代码：

#version 150

in vec2 pass_textureCoords;
in vec3 surfaceNormal;
in vec3 toLightVector;
in vec3 toCamera;
in vec3 playerPosition;
in vec4 vertexPosition;

in float blendPosition;
in float visibility;

out vec4 out_Color;

uniform sampler2D texture0;
uniform sampler2D texture1;

uniform vec3 skyColour;
uniform vec3 light_colour;
uniform float shineDamper;
uniform float reflectivity;

void main(void)
vec3 unitNormal = normalize(surfaceNormal);
vec3 unitLightVector = normalize(toLightVector);

float nDot1 = dot(unitNormal,unitLightVector);
float brightness = max(nDot1,0.2);
vec3 diffuse = brightness * light_colour;

vec3 unitToCamera = normalize(toCamera);
vec3 lightDirection = -unitLightVector;
vec3 reflectedLightDirection = reflect(lightDirection,unitNormal);

float specular = dot(reflectedLightDirection, unitToCamera);
specular = max(specular,0.0);
float damped = pow(specular,shineDamper);
vec3 finalSpecular = damped * reflectivity * light_colour;

out_Color.a = 1;

vec4 fog = vec4(skyColour,1.0);
vec4 diffusion = vec4(diffuse,1.0);

float a = clamp((unitNormal.y - .6)*5 + .5, 0, 0.7);
vec3 texture0_colour = (mix(fog,diffusion * texture(texture0,pass_textureCoords),visibility)).rgb;
vec3 texture1_colour = (mix(fog,diffusion * texture(texture1,pass_textureCoords),visibility)).rgb;

out_Colour.rgb = mix(texture1_colour,texture0_colour,a);

【问题讨论】：

为什么要多次覆盖out_Color？

我是 GLSL 和 OpenGL 的新手。我只是在尝试不同的东西，看看会发生什么

【参考方案1】：

要根据值 a 混合两种纹理，您可以这样做：

float a = ...;
vec3 color0 = texture(texture0, pass_textureCoords).rgb;
vec3 color1 = texture(texture1, pass_textureCoords).rgb;
out_Color.rgb = mix(color0, color1, a);

假设您的unitNormal = (0,1,0) 是向上的方向，如代码所示，则值为

float a = clamp(unitNormal.y, 0, 1);

将导致两个纹理之间的平滑过渡。但是，您可能想要更清晰的过渡，在这种情况下，您可以移动并缩放 unitNormal.y 值以调整过渡的开始和结束位置：

float a = clamp((unitNormal.y - .6)*5 + .5, 0, 1);

【讨论】：

非常感谢。这正是我一直在寻找的。它完美地工作:)