// 城堡损伤：主纹理为 Sprite 原图，damageMask.r 为 1=保留、0=击穿（与城堡同 UV）

CCEffect %{
  techniques:
    - passes:
        - vert: sprite-vs:vert
          frag: castle-damage-fs:frag
          depthStencilState:
            depthTest: false
            depthWrite: false
          blendState:
            targets:
              - blend: true
                blendSrc: src_alpha
                blendDst: one_minus_src_alpha
                blendDstAlpha: one_minus_src_alpha
          rasterizerState:
            cullMode: none
          properties:
            alphaThreshold: { value: 0.5 }
            damageMask: { value: white }
}%

CCProgram sprite-vs %{
precision highp float;
#include <builtin/uniforms/cc-global>
#if USE_LOCAL
  #include <builtin/uniforms/cc-local>
#endif
#if SAMPLE_FROM_RT
  #include <common/common-define>
#endif
in vec3 a_position;
in vec2 a_texCoord;
in vec4 a_color;

out vec4 color;
out vec2 uv0;

vec4 vert() {
  vec4 pos = vec4(a_position, 1.0);
#if USE_LOCAL
  pos = cc_matWorld * pos;
#endif
#if USE_PIXEL_ALIGNMENT
  pos = cc_matView * pos;
  pos.xyz = floor(pos.xyz);
  pos = cc_matProj * pos;
#else
  pos = cc_matViewProj * pos;
#endif
  uv0 = a_texCoord;
#if SAMPLE_FROM_RT
  CC_HANDLE_RT_SAMPLE_FLIP(uv0);
#endif
  color = a_color;
  return pos;
}
}%

CCProgram castle-damage-fs %{
precision highp float;
#include <builtin/internal/embedded-alpha>
#include <builtin/internal/alpha-test>

in vec4 color;
in vec2 uv0;

#pragma builtin(local)
layout(set = 2, binding = 12) uniform sampler2D cc_spriteTexture;

uniform sampler2D damageMask;

vec4 frag() {
  vec4 o = texture(cc_spriteTexture, uv0);
  o *= color;
  float m = texture(damageMask, uv0).r;
  o.a *= m;
  ALPHA_TEST(o);
  return o;
}
}%