opengl - GLSL 水着色器法线在光线经过时变形?
问题描述
我决定按照经典指南使用正弦之和方法编写基本的 GLSL 水着色器。我试图在处理 5 中实现它,在那里我在 PShape 中制作了一个顶点字段来制作一个网格来弄乱。然后,我用我自己的顶点和片段着色器覆盖了默认着色器,并放入了定向光,这样我就可以真正看到法线了。我确保定向光也是可移动的,因此我可以查看法线是否从各个角度工作。
我让波浪正确地形成高度,并且我有某种形式的法线工作,但法线的相互作用真的很奇怪。当我的光线穿过水面的中心轴时,法线似乎在不同的波浪之间变形,并根据光线角度而变化。我捕获的 gif 太大而无法在线发布,所以我确信看到它会比我的话更好地解释:
您应该最大化链接以查看整个图片。注意当光线从左向右平移时,波浪的法线似乎在两组之间变形?当它穿过中心时,这一点尤其明显。这就像法线根据物体被照亮的方向不一致。
中间的球体是使用标准处理着色器的普通球体。我把它留在那里作为参考,以查看海浪并确认我的照明在哪里以及它工作正常。
任何想法我做错了什么?我知道我在某处做错了一些数学。
编辑:建议我添加(冗长的)源代码[我应该从一开始就完成]。顶点着色器:
#define PROCESSING_LIGHT_SHADER
#define MAXWAVES 6
const float pi = 3.14159;
uniform mat4 transform;
uniform mat4 modelview;
uniform mat3 normalMatrix;
uniform float time; //Time since shader started
attribute vec4 position; //Position the vertex from Processing
attribute vec4 color; //Color of the vertex from Processing
attribute vec3 normal; //Normal of the vertex from Processing
attribute vec4 ambient;
attribute vec4 specular;
attribute vec4 emissive;
attribute float shininess;
varying vec4 vertColor; //Color passed on to fragment shader
varying vec4 backVertColor; //Color passed on to fragment shader
uniform float waveLength[MAXWAVES]; //Length of wave
uniform float speed[MAXWAVES]; //Cycle speed of wave
uniform float amplitude[MAXWAVES]; //Wave cycle height
uniform float xDirection[MAXWAVES];
uniform float yDirection[MAXWAVES]; //Flow vector of wave
uniform int lightCount;
uniform vec4 lightPosition[8];
uniform vec3 lightNormal[8];
uniform vec3 lightAmbient[8];
uniform vec3 lightDiffuse[8];
uniform vec3 lightSpecular[8];
uniform vec3 lightFalloff[8];
uniform vec2 lightSpot[8];
varying vec3 Normal;
varying vec3 FragPos;
varying vec3 Vec;
varying vec3 lightDir;
//Some constants that the processing shader used
const float zero_float = 0.0;
const float one_float = 1.0;
const vec3 zero_vec3 = vec3(0);
float falloffFactor(vec3 lightPos, vec3 vertPos, vec3 coeff) {
vec3 lpv = lightPos - vertPos;
vec3 dist = vec3(one_float);
dist.z = dot(lpv, lpv);
dist.y = sqrt(dist.z);
return one_float / dot(dist, coeff);
}
float spotFactor(vec3 lightPos, vec3 vertPos, vec3 lightNorm, float minCos, float spotExp) {
vec3 lpv = normalize(lightPos - vertPos);
vec3 nln = -one_float * lightNorm;
float spotCos = dot(nln, lpv);
return spotCos <= minCos ? zero_float : pow(spotCos, spotExp);
}
float lambertFactor(vec3 lightDir, vec3 vecNormal) {
return max(zero_float, dot(lightDir, vecNormal));
}
float blinnPhongFactor(vec3 lightDir, vec3 vertPos, vec3 vecNormal, float shine) {
vec3 np = normalize(vertPos);
vec3 ldp = normalize(lightDir - np);
return pow(max(zero_float, dot(ldp, vecNormal)), shine);
}
//Returns the height of a vertex given a single wave param
float WaveHeight(int waveNumber, float x, float y) {
vec2 direction = (vec2(xDirection[waveNumber], yDirection[waveNumber]));
float frequency = 2.0*pi/waveLength[waveNumber];
float phase = speed[waveNumber] * frequency;
float theta = dot(direction, vec2(x, y));
return amplitude[waveNumber] * sin(theta * frequency + time * phase);
}
//Returns height of a vertex given all the active waves
// and its current x/y value
float WaveSum(float x, float y)
{
float height = 0.0;
for(int i = 0; i < MAXWAVES; i++)
{
height += WaveHeight(i, x, y);
}
return height;
}
float getDy(int waveNumber, float x, float y) {
vec2 direction = (vec2(xDirection[waveNumber], yDirection[waveNumber]));
float frequency = 2.0*pi/waveLength[waveNumber];
float phase = speed[waveNumber] * frequency;
float theta = dot(direction, vec2(x, y));
float A = amplitude[waveNumber] * direction.y * frequency;
return A * cos(theta * frequency + time * phase);
}
float getDx(int waveNumber, float x, float y) {
vec2 direction = (vec2(xDirection[waveNumber], yDirection[waveNumber]));
float frequency = 2.0*pi/waveLength[waveNumber];
float phase = speed[waveNumber] * frequency;
float theta = dot(direction, vec2(x, y));
float A = amplitude[waveNumber] * direction.x * frequency;
return A * cos(theta * frequency + time * phase);
}
//Returns the normal vector for each vertex
vec3 getNormal(float x, float y) {
float dx = 0.0;
float dy = 0.0;
//Sum for each wave
for (int i = 0; i < MAXWAVES; i++) {
dx += getDx(i, x, y);
dy += getDy(i, x, y);
}
vec3 n = vec3(-dx, -dy, 1.0);
return normalize(n);
}
void main() {
vec4 pos = position; //Grab the position from Processing bc it's read only
pos.z = WaveSum(pos.x, pos.y);
gl_Position = transform * pos; //Get clipping matrix for view
vec3 ecVertex = vec3(modelview * pos);
// Normal vector in eye coordinates
vec3 Normal = getNormal(pos.x, pos.y);
vec3 ecNormal = normalize(normalMatrix * Normal);
vec3 ecNormalInv = ecNormal * -one_float;
// Light calculations
vec3 totalAmbient = vec3(0, 0, 0);
vec3 totalFrontDiffuse = vec3(0, 0, 0);
vec3 totalFrontSpecular = vec3(0, 0, 0);
vec3 totalBackDiffuse = vec3(0, 0, 0);
vec3 totalBackSpecular = vec3(0, 0, 0);
for (int i = 0; i < 8; i++) {
if (lightCount == i) break;
vec3 lightPos = lightPosition[i].xyz;
bool isDir = lightPosition[i].w < one_float;
float spotCos = lightSpot[i].x;
float spotExp = lightSpot[i].y;
vec3 lightDir;
float falloff;
float spotf;
if (isDir) {
falloff = one_float;
lightDir = -one_float * lightNormal[i];
} else {
falloff = falloffFactor(lightPos, ecVertex, lightFalloff[i]);
lightDir = normalize(lightPos - ecVertex);
}
spotf = spotExp > zero_float ? spotFactor(lightPos, ecVertex, lightNormal[i],
spotCos, spotExp)
: one_float;
if (any(greaterThan(lightAmbient[i], zero_vec3))) {
totalAmbient += lightAmbient[i] * falloff;
}
if (any(greaterThan(lightDiffuse[i], zero_vec3))) {
totalFrontDiffuse += lightDiffuse[i] * falloff * spotf *
lambertFactor(lightDir, ecNormal);
totalBackDiffuse += lightDiffuse[i] * falloff * spotf *
lambertFactor(lightDir, ecNormalInv);
}
if (any(greaterThan(lightSpecular[i], zero_vec3))) {
totalFrontSpecular += lightSpecular[i] * falloff * spotf *
blinnPhongFactor(lightDir, ecVertex, ecNormal, shininess);
totalBackSpecular += lightSpecular[i] * falloff * spotf *
blinnPhongFactor(lightDir, ecVertex, ecNormalInv, shininess);
}
}
// Calculating final color as result of all lights (plus emissive term).
// Transparency is determined exclusively by the diffuse component.
vertColor =
vec4(totalFrontDiffuse, 1) * color;
backVertColor =
vec4(totalBackDiffuse, 1) * color;
}
片段着色器:
#ifdef GL_ES
precision mediump float;
precision mediump int;
#endif
varying vec4 vertColor; //Color from vertshader
varying vec4 backVertColor; //Color from vertshader
void main() {
gl_FragColor = gl_FrontFacing ? vertColor : backVertColor;
}
解决方案
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