shadow.vert

// Appologies for the messy code.
// It was run through SPIRV-Cross
// I cleaned it up and renamed the variables by hand.

#version 330

layout(std140) uniform Locals
{
    mat2x4 LightMatrix;
    float LightRadius;
} _68;

layout(std140) uniform DriftGlobals
{
    mat2x4 DRIFT_MATRIX_V;
    mat2x4 DRIFT_MATRIX_P;
    mat2x4 DRIFT_MATRIX_VP;
    mat2x4 DRIFT_MATRIX_VP_INV;
    mat2x4 DRIFT_MATRIX_REPROJ;
    vec2 DRIFT_PIXEL_EXTENTS;
    vec2 DRIFT_SCREEN_EXTENTS;
    vec2 DRIFT_BUFFER_EXTENTS;
    float DRIFT_ATLAS_SIZE;
} _155;

layout(location = 0) in vec2 IN_occluder_coord;
layout(location = 1) in vec4 IN_endpoints;
out float FRAG_opacity;
out vec4 FRAG_penumbras;
out vec3 FRAG_edges;
out vec4 FRAG_light_position;
out vec4 FRAG_endpoints;

vec3 _719;

void main()
{
    vec2 light_pos = vec3(0.0, 0.0, 1.0) * mat2x3(_68.LightMatrix[0].xyz, _68.LightMatrix[1].xyz);
    vec2 occluder_coord_x = vec2(IN_occluder_coord.x);
    vec2 endpoint = mix(IN_endpoints.zw, IN_endpoints.xy, occluder_coord_x);
    vec2 delta_a = IN_endpoints.zw - light_pos;
    vec2 delta_b = IN_endpoints.xy - light_pos;
    vec2 delta = endpoint - light_pos;
    float neg_LightRadius = -_68.LightRadius;
    vec2 offset_a = (vec2(neg_LightRadius, _68.LightRadius) * 1.0) * normalize(delta_a).yx;
    vec2 offset_b = (vec2(_68.LightRadius, neg_LightRadius) * 1.0) * normalize(delta_b).yx;
    vec2 offset = mix(offset_a, offset_b, occluder_coord_x);
    vec2 swept_edge = delta - offset;
    vec2 w = vec2(IN_occluder_coord.y);
    vec2 proj_pos_xy = mix(swept_edge, endpoint, w);
    float proj_pos_x = proj_pos_xy.x;
    vec2 neg_delta_a = -delta_a;
    vec2 neg_offset_b = -offset_b;

    vec2 seg_delta = IN_endpoints.xy - IN_endpoints.zw;
    float one_minus_w = 1.0 - IN_occluder_coord.y;
    vec2 delta_sum = delta_a + delta_b;
    vec2 edges_xy = -((delta - (offset * one_minus_w)) * mat2(vec2(delta_sum.y, -delta_sum.x), vec2(-seg_delta.y, seg_delta.x)));
    vec3 edges = vec3(edges_xy.x, 2*edges_xy.y, 0);
    edges.z = dot(seg_delta.yx * vec2(-1.0, 1.0), swept_edge) * one_minus_w;
    gl_Position = vec4(vec3(proj_pos_x, proj_pos_xy.y, IN_occluder_coord.y) * mat2x3(_155.DRIFT_MATRIX_VP[0].xyz, _155.DRIFT_MATRIX_VP[1].xyz), 0.0, IN_occluder_coord.y);
    FRAG_opacity = 1.0;
    FRAG_edges = edges;
    FRAG_light_position = vec4(proj_pos_x, proj_pos_xy.y, 0.0, IN_occluder_coord.y * 16.0);
    FRAG_endpoints = vec4(IN_endpoints.zwxy) * vec4(0.0625);
	
    // If I write garbage to one of the components first, then I can succussfully write the other components.
    // Neither the conditional nor garbage value written seems to matter as long as it's not optimized out.
    // If I skip the conditional or overwrite it with a the real value, then I get garbage in the frag shader.
    FRAG_penumbras.w = delta.x > delta.x ? 0 : 0;
    FRAG_penumbras.x = dot(delta - mix(offset, delta_a, w), vec2(neg_delta_a.y, -neg_delta_a.x));
    FRAG_penumbras.y = dot(delta - mix(offset, delta_a, w), vec2(-offset_a.y, offset_a.x));
    FRAG_penumbras.z = dot(delta - mix(offset, delta_b, w), vec2(delta_b.y, -delta_b.x));
//    FRAG_penumbras.w = dot(delta - mix(offset, delta_b, w), vec2(-neg_offset_b.y, neg_offset_b.x));
}