I am implementing a ray tracer with mesh points in WebGL. Few words for my implementation.
I am passing vertex values and vertex normals in textures and I unpack them in the fragment shader where the ray tracing algorithm is executed. The spheres consisting of triangles had a flat shaded look, then I multiplied the vertex normals of the triangle with the barycentric coords and I had the smooth look in the triangle spheres. The problem is when I calculate the shadow, it has the same "edgy" look. Ill provide a print screen of the result and the code of how I currently calculate the shadow rays.
As you see the sphere surface appears smooth but the shadow is not.
here is the calcShadow function i use:
vec3 calcShadow(Sphere lightSource, vec3 hitPos){
vec3 color;
vec3 lightDir = normalize(lightSource.center-hitPos);
Ray shadowRay = Ray(hitPos, lightDir);
float isHitLight = hitLightSource(shadowRay,lightSource);
float isHitMesh = hitMesh(shadowRay);
if (isHitMesh < isHitLight) {
color = vec3(0.5,0.5,0.5);
}else{
color = vec3(1.,1.,1.);
}
return color;
}
the hitMesh:
float hitMesh(Ray R_){
float mindist = 1000.;
vec4 a = vec4(0.0), b = vec4(0.0), c = vec4(0.0);
vec3 intersect = vec3(0.0,0.0,0.0);
for (int i = 0; i < vertsCount; i += 3) {
a = texelFetch(uMeshData, ivec2(i, 0), 0);
b = texelFetchOffset(uMeshData, ivec2(i, 0), 0, ivec2(1, 0));
c = texelFetchOffset(uMeshData, ivec2(i, 0), 0, ivec2(2, 0));
vec3 triangleNormal;
vec3 uvt;
float z;
bool isHit = hitTriangleSecond(R_.orig, R_.dir, a.xyz, b.xyz, c.xyz, uvt, triangleNormal, intersect, z);;
if (isHit) {
if (z<mindist && z > 0.001) mindist = z;
}
}
return mindist;
}
and this is the hitTriangke second method for the triangle intersection test:
bool hitTriangleSecond( vec3 orig, vec3 dir, vec3 a, vec3 b, vec3 c,
out vec3 uvt, out vec3 N, out vec3 x, out float dist) {
float eps=1e-8;
vec3 ab = b - a;
vec3 ac = c - a;
N = normalize(cross(ab, ac));
dist = dot(a - orig, N) / dot(dir, N);
x = orig + dir * dist;
vec3 ax = x - a;
float d00 = dot(ab, ab);
float d01 = dot(ab, ac);
float d11 = dot(ac, ac);
float d20 = dot(ax, ab);
float d21 = dot(ax, ac);
float denom = d00 * d11 - d01 * d01; // determinant
// if the determinant is negative the triangle is backfacing
// if the determinant is close to 0, the ray misses the triangl
if ( denom <= eps )
return false;
uvt.y = (d11 * d20 - d01 * d21) / denom;
if ( uvt.y < 0.0 || uvt.y > 1.0 )
return false;
uvt.z = (d00 * d21 - d01 * d20) / denom;
if ( uvt.z < 0.0 || uvt.z > 1.0 )
return false;
uvt.x = 1.0 - uvt.y - uvt.z;
if ( uvt.x < 0.0 || uvt.x > 1.0 )
return false;
return true;
}
I know that there is no calculation of the interpolated triangle normal but my question is, Do I need to update the hitTriangle function to return the interpolated normal, based on the vertex normals? or I need to calculate the barycentric coords and then insert it to the hit triangle function? I kinda not understand how to implement smooth shadows...
below is my trace for loop where I unpack the mesh and calculate the interpolated normal of the hit and this is how I got the smooth surface look:
for (int i = 0; i < vertsCount; i += 3) {
a = texelFetch(uMeshData, ivec2(i, 0), 0);
b = texelFetchOffset(uMeshData, ivec2(i, 0), 0, ivec2(1, 0));
c = texelFetchOffset(uMeshData, ivec2(i, 0), 0, ivec2(2, 0));
aN = texelFetch(uNormData, ivec2(i, 0), 0);
bN = texelFetchOffset(uNormData, ivec2(i, 0), 0, ivec2(1, 0));
cN = texelFetchOffset(uNormData, ivec2(i, 0), 0, ivec2(2, 0));
vec3 uvt;
vec3 intersect;
float z;
bool isHit = hitTriangleSecond(R_.orig, R_.dir, a.xyz, b.xyz, c.xyz, uvt, triangleNormal, intersect, z);
if (isHit) {
if (z<mindist && z > 0.001) {
hitPos1 = intersect;
mindist = z;
weHitSomething = true;
material.type = DIEL;
material.albedo = vec3(.8, .3, .4);
normal = aN.xyz*uvt.x + bN.xyz*uvt.y + cN.xyz*uvt.z;
hitPos = hitPos1;
}
}
}
