cocos-creator-template/assets/chunks/shading-entries/main-functions/misc/sky-vs.chunk

#include <surfaces/default-functions/common-vs>
#include <surfaces/module-functions/common-vs>

vec4 CalcSkyClipPos(vec3 viewDir)
{
    vec4 clipPos;
    // Clip Space
    mat4 matViewRotOnly = mat4(mat3(cc_matView));
    vec4 pos = matViewRotOnly * vec4(viewDir, 1.0);

    // orthographic projection adaptation
    if (cc_matProj[3].w > 0.0) {
        mat4 matProj = cc_matProj;
        // default ortho height 10 approximate to default FOV 45
        // stretch x by 2 to remedy perspective effect
        // w = sin(45/2), h = 2 * w, _11 = 2 / w, _22 = 2 / h
        matProj[0].x = 5.2;
        matProj[1].y = 2.6;
        matProj[2].zw = vec2(-1.0);
        matProj[3].zw = vec2(0.0);
        // position is modified inside branches to work around a vk driver bug seen in
        // low-end Qualcomm devices (Adreno 512, Oppo R11, cocos-creator/3d-tasks#9236)
        clipPos = matProj * pos;
    }
    else {
        clipPos = cc_matProj * pos;
    }

    clipPos.z = 0.99999 * clipPos.w;
    return clipPos;
}

void main()
{
    SurfacesStandardVertexIntermediate In;

    // Local Space
    CCSurfacesVertexInput(In);

    // cc_matWorld is undefined, so can not use mat4(mat3(cc_matWorld))
    In.worldPos = In.position.xyz;
    In.worldPos = SurfacesVertexModifyWorldPos(In);

    In.clipPos = CalcSkyClipPos(In.position.xyz);

    In.worldNormal.w = 1.0;
    In.worldNormal.xyz = normalize(In.position.xyz);

    // Other Data
#if CC_USE_FOG != CC_FOG_NONE && !CC_USE_ACCURATE_FOG
    In.fogFactor = 0.0;
#endif

    CCSurfacesVertexOutput(In);
}