视差映射期间奇怪的分层效果
Weird Layered Effect During Parallax Mapping
我正在按照 LearnOpenGL 指南进行操作，并正在尝试实施 Steep Parallax Mapping。
除了我的砖墙似乎有明显的可见层，而指南中的照片没有显示任何层外，一切似乎都很好。我试图使用这段代码来视差世界的地形，但这些奇怪的层似乎也出现在那里，所以我希望找到解决这个问题的办法。
Layered wall photo
[1
Photo of how it should look
这是我修改过的顶点着色器
#version 300 es
in vec4 vPosition; // aPos
in vec2 texCoord; // aTexCoords
in vec4 vNormal; // aNormal
in vec4 vTangent; // aTangent
uniform mat4 model_view;
uniform mat4 projection;
uniform vec4 light_position;
out vec2 ftexCoord;
out vec3 vT;
out vec3 vN;
out vec4 position;
out vec3 FragPos;
out vec3 TangentLightPos;
out vec3 TangentViewPos;
out vec3 TangentFragPos;
void
main()
{
// Normal variables
vN = normalize(model_view * vNormal).xyz;
vT = normalize(model_view * vTangent).xyz;
vec4 veyepos = model_view*vPosition;
position = veyepos;
ftexCoord = texCoord;
// Displacement variables
vec3 bi = cross(vT, vN);
FragPos = vec3(model_view * vPosition).xyz;
vec3 T = normalize(mat3(model_view) * vTangent.xyz);
vec3 B = normalize(mat3(model_view) * bi);
vec3 N = normalize(mat3(model_view) * vNormal.xyz);
mat3 TBN = transpose(mat3(T, B, N));
TangentLightPos = TBN * light_position.xyz;
TangentViewPos = TBN * vPosition.xyz;
TangentFragPos = TBN * FragPos;
gl_Position = projection * model_view * vPosition;
}
我修改过的片段着色器在这里
#version 300 es
precision highp float;
in vec2 ftexCoord;
in vec3 vT; //parallel to surface in eye space
in vec3 vN; //perpendicular to surface in eye space
in vec4 position;
in vec3 FragPos;
in vec3 TangentLightPos;
in vec3 TangentViewPos;
in vec3 TangentFragPos;
uniform int mode;
uniform vec4 light_position;
uniform vec4 light_color;
uniform vec4 ambient_light;
uniform sampler2D colorMap;
uniform sampler2D normalMap;
uniform sampler2D depthMap;
out vec4 fColor;
// STEEP PARALLAX MAPPING
vec2 ParallaxMapping(vec2 texCoords, vec3 viewDir)
{
// number of depth layers
const float minLayers = 8.0;
const float maxLayers = 32.0;
float numLayers = mix(maxLayers, minLayers, abs(dot(vec3(0.0, 0.0, 1.0), viewDir)));
// calculate the size of each layer
float layerDepth = 1.0 / numLayers;
// depth of current layer
float currentLayerDepth = 0.0;
// the amount to shift the texture coordinates per layer (from vector P)
vec2 P = viewDir.xy / viewDir.z * 0.1;
vec2 deltaTexCoords = P / numLayers;
// get initial values
vec2 currentTexCoords = texCoords;
float currentDepthMapValue = texture(depthMap, currentTexCoords).r;
while(currentLayerDepth < currentDepthMapValue)
{
// shift texture coordinates along direction of P
currentTexCoords -= deltaTexCoords;
// get depthmap value at current texture coordinates
currentDepthMapValue = texture(depthMap, currentTexCoords).r;
// get depth of next layer
currentLayerDepth += layerDepth;
}
return currentTexCoords;
}
void main()
{
// DO NORMAL MAPPING
if (mode == 0) {
vec3 T = normalize(vT);
vec3 N = normalize(vN);
vec3 bi = cross(T, N);
mat4 changeOfCoord = mat4(vec4(T, 0), vec4(bi, 0), vec4(N, 0), vec4(0, 0, 0, 1));
vec3 L = normalize(light_position - position).xyz;
vec3 E = normalize(-position).xyz;
vec4 text = vec4(texture(normalMap, ftexCoord) * 2.0 - 1.0);
vec4 eye = changeOfCoord * text;
vec4 amb = texture(colorMap, ftexCoord) * ambient_light;
vec4 diff = max(0.0, dot(L, eye.xyz)) * light_color * texture(colorMap, ftexCoord);
fColor = amb + diff;
} else if (mode == 1) { // DO PARALLAX MAPPING
// offset texture coordinates with Parallax Mapping
vec3 viewDir = normalize(TangentViewPos - TangentFragPos);
vec2 texCoords = ftexCoord;
texCoords = ParallaxMapping(ftexCoord, viewDir);
// discard samples outside of the default texture coordinate space
if(texCoords.x > 1.0 || texCoords.y > 1.0 || texCoords.x < 0.0 || texCoords.y < 0.0)
discard;
// obtain normal from normal map
vec3 normal = texture(normalMap, texCoords).rgb;
//values stored in normal texture is [0,1] range, we need [-1, 1] range
normal = normalize(normal * 2.0 - 1.0);
// get diffuse color
vec3 color = texture(colorMap, texCoords).rgb;
// ambient
vec3 ambient = 0.1 * color;
// diffuse
vec3 lightDir = normalize(TangentLightPos - TangentFragPos);
float diff = max(dot(lightDir, normal), 0.0);
vec3 diffuse = diff * color;
// specular
vec3 reflectDir = reflect(lightDir, normal);
vec3 halfwayDir = normalize(lightDir + viewDir);
float spec = pow(max(dot(normal, halfwayDir), 0.0), 32.0);
vec3 specular = vec3(0.2) * spec;
fColor = vec4(ambient + diffuse + 0.0, 1.0);
}
}
锐角的图层是视差贴图的常见效果。要改善结果，您必须增加样本数量或实施视差遮挡映射（如本教程底部所述）：
// STEEP PARALLAX MAPPING
vec2 ParallaxMapping(vec2 texCoords, vec3 viewDir)
{
// number of depth layers
const float minLayers = 8.0;
const float maxLayers = 32.0;
float numLayers = mix(maxLayers, minLayers, abs(dot(vec3(0.0, 0.0, 1.0), viewDir)));
// calculate the size of each layer
float layerDepth = 1.0 / numLayers;
// depth of current layer
float currentLayerDepth = 0.0;
// the amount to shift the texture coordinates per layer (from vector P)
vec2 P = viewDir.xy / viewDir.z * 0.1;
vec2 deltaTexCoords = P / numLayers;
// get initial values
vec2 currentTexCoords = texCoords;
float currentDepthMapValue = texture(depthMap, currentTexCoords).r;
while(currentLayerDepth < currentDepthMapValue)
{
// shift texture coordinates along direction of P
currentTexCoords -= deltaTexCoords;
// get depthmap value at current texture coordinates
currentDepthMapValue = texture(depthMap, currentTexCoords).r;
// get depth of next layer
currentLayerDepth += layerDepth;
}
// get texture coordinates before collision (reverse operations)
vec2 prevTexCoords = currentTexCoords + deltaTexCoords;
// get depth after and before collision for linear interpolation
float afterDepth = currentDepthMapValue - currentLayerDepth;
float beforeDepth = texture(depthMap, prevTexCoords).r - currentLayerDepth + layerDepth;
// interpolation of texture coordinates
float weight = afterDepth / (afterDepth - beforeDepth);
vec2 finalTexCoords = prevTexCoords * weight + currentTexCoords * (1.0 - weight);
return finalTexCoords;
}
顺便说一句，向量似乎是倒置的。通常，双切线是 Cross product of the normal vector and the tangent in a Right-handed 系统。但这取决于位移纹理。
vec3 bi = cross(vT, vN);
vec3 bi = cross(vN, vT);
进一步查看：
Bump Mapping with javascript and glsl
Normal, Parallax and Relief mapping
Demo
我正在按照 LearnOpenGL 指南进行操作，并正在尝试实施 Steep Parallax Mapping。
除了我的砖墙似乎有明显的可见层，而指南中的照片没有显示任何层外，一切似乎都很好。我试图使用这段代码来视差世界的地形，但这些奇怪的层似乎也出现在那里，所以我希望找到解决这个问题的办法。
Layered wall photo
[
Photo of how it should look
这是我修改过的顶点着色器
#version 300 es
in vec4 vPosition; // aPos
in vec2 texCoord; // aTexCoords
in vec4 vNormal; // aNormal
in vec4 vTangent; // aTangent
uniform mat4 model_view;
uniform mat4 projection;
uniform vec4 light_position;
out vec2 ftexCoord;
out vec3 vT;
out vec3 vN;
out vec4 position;
out vec3 FragPos;
out vec3 TangentLightPos;
out vec3 TangentViewPos;
out vec3 TangentFragPos;
void
main()
{
// Normal variables
vN = normalize(model_view * vNormal).xyz;
vT = normalize(model_view * vTangent).xyz;
vec4 veyepos = model_view*vPosition;
position = veyepos;
ftexCoord = texCoord;
// Displacement variables
vec3 bi = cross(vT, vN);
FragPos = vec3(model_view * vPosition).xyz;
vec3 T = normalize(mat3(model_view) * vTangent.xyz);
vec3 B = normalize(mat3(model_view) * bi);
vec3 N = normalize(mat3(model_view) * vNormal.xyz);
mat3 TBN = transpose(mat3(T, B, N));
TangentLightPos = TBN * light_position.xyz;
TangentViewPos = TBN * vPosition.xyz;
TangentFragPos = TBN * FragPos;
gl_Position = projection * model_view * vPosition;
}
我修改过的片段着色器在这里
#version 300 es
precision highp float;
in vec2 ftexCoord;
in vec3 vT; //parallel to surface in eye space
in vec3 vN; //perpendicular to surface in eye space
in vec4 position;
in vec3 FragPos;
in vec3 TangentLightPos;
in vec3 TangentViewPos;
in vec3 TangentFragPos;
uniform int mode;
uniform vec4 light_position;
uniform vec4 light_color;
uniform vec4 ambient_light;
uniform sampler2D colorMap;
uniform sampler2D normalMap;
uniform sampler2D depthMap;
out vec4 fColor;
// STEEP PARALLAX MAPPING
vec2 ParallaxMapping(vec2 texCoords, vec3 viewDir)
{
// number of depth layers
const float minLayers = 8.0;
const float maxLayers = 32.0;
float numLayers = mix(maxLayers, minLayers, abs(dot(vec3(0.0, 0.0, 1.0), viewDir)));
// calculate the size of each layer
float layerDepth = 1.0 / numLayers;
// depth of current layer
float currentLayerDepth = 0.0;
// the amount to shift the texture coordinates per layer (from vector P)
vec2 P = viewDir.xy / viewDir.z * 0.1;
vec2 deltaTexCoords = P / numLayers;
// get initial values
vec2 currentTexCoords = texCoords;
float currentDepthMapValue = texture(depthMap, currentTexCoords).r;
while(currentLayerDepth < currentDepthMapValue)
{
// shift texture coordinates along direction of P
currentTexCoords -= deltaTexCoords;
// get depthmap value at current texture coordinates
currentDepthMapValue = texture(depthMap, currentTexCoords).r;
// get depth of next layer
currentLayerDepth += layerDepth;
}
return currentTexCoords;
}
void main()
{
// DO NORMAL MAPPING
if (mode == 0) {
vec3 T = normalize(vT);
vec3 N = normalize(vN);
vec3 bi = cross(T, N);
mat4 changeOfCoord = mat4(vec4(T, 0), vec4(bi, 0), vec4(N, 0), vec4(0, 0, 0, 1));
vec3 L = normalize(light_position - position).xyz;
vec3 E = normalize(-position).xyz;
vec4 text = vec4(texture(normalMap, ftexCoord) * 2.0 - 1.0);
vec4 eye = changeOfCoord * text;
vec4 amb = texture(colorMap, ftexCoord) * ambient_light;
vec4 diff = max(0.0, dot(L, eye.xyz)) * light_color * texture(colorMap, ftexCoord);
fColor = amb + diff;
} else if (mode == 1) { // DO PARALLAX MAPPING
// offset texture coordinates with Parallax Mapping
vec3 viewDir = normalize(TangentViewPos - TangentFragPos);
vec2 texCoords = ftexCoord;
texCoords = ParallaxMapping(ftexCoord, viewDir);
// discard samples outside of the default texture coordinate space
if(texCoords.x > 1.0 || texCoords.y > 1.0 || texCoords.x < 0.0 || texCoords.y < 0.0)
discard;
// obtain normal from normal map
vec3 normal = texture(normalMap, texCoords).rgb;
//values stored in normal texture is [0,1] range, we need [-1, 1] range
normal = normalize(normal * 2.0 - 1.0);
// get diffuse color
vec3 color = texture(colorMap, texCoords).rgb;
// ambient
vec3 ambient = 0.1 * color;
// diffuse
vec3 lightDir = normalize(TangentLightPos - TangentFragPos);
float diff = max(dot(lightDir, normal), 0.0);
vec3 diffuse = diff * color;
// specular
vec3 reflectDir = reflect(lightDir, normal);
vec3 halfwayDir = normalize(lightDir + viewDir);
float spec = pow(max(dot(normal, halfwayDir), 0.0), 32.0);
vec3 specular = vec3(0.2) * spec;
fColor = vec4(ambient + diffuse + 0.0, 1.0);
}
}
锐角的图层是视差贴图的常见效果。要改善结果，您必须增加样本数量或实施视差遮挡映射（如本教程底部所述）：
// STEEP PARALLAX MAPPING
vec2 ParallaxMapping(vec2 texCoords, vec3 viewDir)
{
// number of depth layers
const float minLayers = 8.0;
const float maxLayers = 32.0;
float numLayers = mix(maxLayers, minLayers, abs(dot(vec3(0.0, 0.0, 1.0), viewDir)));
// calculate the size of each layer
float layerDepth = 1.0 / numLayers;
// depth of current layer
float currentLayerDepth = 0.0;
// the amount to shift the texture coordinates per layer (from vector P)
vec2 P = viewDir.xy / viewDir.z * 0.1;
vec2 deltaTexCoords = P / numLayers;
// get initial values
vec2 currentTexCoords = texCoords;
float currentDepthMapValue = texture(depthMap, currentTexCoords).r;
while(currentLayerDepth < currentDepthMapValue)
{
// shift texture coordinates along direction of P
currentTexCoords -= deltaTexCoords;
// get depthmap value at current texture coordinates
currentDepthMapValue = texture(depthMap, currentTexCoords).r;
// get depth of next layer
currentLayerDepth += layerDepth;
}
// get texture coordinates before collision (reverse operations)
vec2 prevTexCoords = currentTexCoords + deltaTexCoords;
// get depth after and before collision for linear interpolation
float afterDepth = currentDepthMapValue - currentLayerDepth;
float beforeDepth = texture(depthMap, prevTexCoords).r - currentLayerDepth + layerDepth;
// interpolation of texture coordinates
float weight = afterDepth / (afterDepth - beforeDepth);
vec2 finalTexCoords = prevTexCoords * weight + currentTexCoords * (1.0 - weight);
return finalTexCoords;
}
顺便说一句，向量似乎是倒置的。通常，双切线是 Cross product of the normal vector and the tangent in a Right-handed 系统。但这取决于位移纹理。
vec3 bi = cross(vT, vN);
vec3 bi = cross(vN, vT);
进一步查看：
Bump Mapping with javascript and glsl
Normal, Parallax and Relief mapping
Demo