我正处于制作 SceneKit 着色器修改器(用于几何入口点)的早期阶段,该修改器根据高度图纹理置换平面的几何形状。计划是用它来创建地形。
在 iOS(编辑:iOS 模拟器)中,着色器按其应有的方式工作,但会将此警告打印到控制台:
SceneKit:错误,没有代码的修饰符无效
然而,当为 OS X 构建时,着色器会出现致命错误,并且地形几何图形仅显示为粉红色矩形。
这是几何着色器修改器:
uniform sampler2D displacementMap;
const float intensity = 7.5;
# pragma body
vec4 displace = texture2D(displacementMap, _geometry.texcoords[0]);
_geometry.position.z += displace.r * intensity;
这就是着色器与几何体的连接方式。terrainScene
是高度图,它被放置在漫反射内容和自定义内容中displacementMap
着色器修改器中的采样器值:
//displacement shader
let mat = SCNMaterial()
mat.diffuse.contents = terrainScene
var displacementShader: String?
guard let path = NSBundle.mainBundle().pathForResource("DisplaceGeometry", ofType: "shader") else {return}
do {
displacementShader = try String(contentsOfFile: path, encoding: NSUTF8StringEncoding)
} catch {
return
}
mat.shaderModifiers = [SCNShaderModifierEntryPointGeometry: displacementShader!]
let noiseProperty = SCNMaterialProperty(contents: terrainScene!)
mat.setValue(noiseProperty, forKey: "displacementMap")
//geometry
let plane = SCNPlane(width: 80, height: 80)
plane.widthSegmentCount = 40
plane.heightSegmentCount = 40
plane.materials = [mat]
这是 OS X 错误消息的开头:
SceneKit: error, modifier without code is invalid
2016-06-11 10:58:32.054 EndlessTerrainOSX[16923:5292387] SceneKit: error, Invalid shader modifier : no code provided
2016-06-11 10:58:32.640 EndlessTerrainOSX[16923:5292387] FATAL ERROR : failed loading compiling shader:
以及错误的结束:
UserInfo={NSLocalizedDescription=Compilation failed:
<program source>:343:8: error: global variables must have a constant address space qualifier
float4 displace = displacementMap.sample(displacementMapSampler, _geometry.texcoords[0]);
^
<program source>:343:19: error: use of undeclared identifier 'displacementMap'
float4 displace = displacementMap.sample(displacementMapSampler, _geometry.texcoords[0]);
^
<program source>:343:42: error: use of undeclared identifier 'displacementMapSampler'
float4 displace = displacementMap.sample(displacementMapSampler, _geometry.texcoords[0]);
^
<program source>:344:1: error: unknown type name '_geometry'
_geometry.position.z += displace.r * intensity;
^
<program source>:344:10: error: cannot use dot operator on a type
_geometry.position.z += displace.r * intensity;
^
}
2016-06-11 10:58:32.646 EndlessTerrainOSX[16923:5292387] Shaders without a vertex function are not allowed
有谁知道为什么它在 iOS 上显示,但在 OS X 上失败?