SceneKit水就像Badger的例子

Question

enybody是否知道如何在Apple的獾示例中创建水材料？

有一个＆＃34; geotherm_01＆＃34;对象＆＃34; scene.scn＆＃34;这个对象得到了材料＆＃34; _1_terrasses_orange_water＆＃34;和＆＃34; _1_terrasses_eau＆＃34;这会产生看似逼真的慢动画水。

我试图在我的测试项目中重复使用相同的材​​料，但却无法获得相同的结果。

Answer 1

使用shader modifiers实现此水效果，如Xcode中的SceneKit场景编辑器所示。最重要的材料属性是normal map，它将用于影响光照，以便在完美平坦的几何体上模拟小波。

更具体地说，.surface入口点的修饰符是

float waterSpeed = u_time * -0.1;vec2 uvs = _surface.normalTexcoord;uvs.x *= 2;vec3 tn = texture2D(u_normalTexture, vec2(uvs.x, uvs.y + waterSpeed)).xyz;tn = tn * 2 - 1;vec3 tn2 = texture2D(u_normalTexture, vec2(uvs.x + 0.35 , uvs.y + 0.35 + (waterSpeed * 1.3))).xyz;tn2 = tn2 * 2 - 1;vec3 rn = (tn + tn2) * 0.5;mat3 ts = mat3(_surface.tangent, _surface.bitangent, _surface.geometryNormal);_surface.normal = normalize(ts * rn);

以下是代码的注释版本：

// Elapsed time in seconds
float waterSpeed = u_time * -0.1;

// Texture coordinates that will be used to sample the normal map
vec2 uvs = _surface.normalTexcoord;
uvs.x *= 2;

// Sample the normal map
vec3 tn = texture2D(u_normalTexture, vec2(uvs.x, uvs.y + waterSpeed)).xyz;

// The texture stores values in the [0, 1] range
// Express the coordinates of the normal vector in the [-1, +1] range
tn = tn * 2 - 1;

// Sample the normal map again, using the `waterSpeed` offset this time
// in order to produce the animation effect
vec3 tn2 = texture2D(u_normalTexture, vec2(uvs.x + 0.35 , uvs.y + 0.35 + (waterSpeed * 1.3))).xyz;
tn2 = tn2 * 2 - 1;

// Combine the two normals (static and animated) to produce a richer (more complex and less uniform) effect
vec3 rn = (tn + tn2) * 0.5;

// Normals in the normal map are expressed in tangent space
// Convert them to object space and override the surface normal to simulate wavelets
mat3 ts = mat3(_surface.tangent, _surface.bitangent, _surface.geometryNormal);
_surface.normal = normalize(ts * rn);