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#[vertex]
#version 450
#VERSION_DEFINES
layout(location = 0) in vec3 vertex_attrib;
layout(location = 0) out float depth_interp;
layout(location = 1) out flat uint element_index;
layout(push_constant, binding = 0, std430) uniform Params {
uint base_index;
uint pad0;
uint pad1;
uint pad2;
}
params;
layout(set = 0, binding = 1, std140) uniform State {
mat4 projection;
float inv_z_far;
uint screen_to_clusters_shift; // shift to obtain coordinates in block indices
uint cluster_screen_width; //
uint cluster_data_size; // how much data for a single cluster takes
uint cluster_depth_offset;
uint pad0;
uint pad1;
uint pad2;
}
state;
struct RenderElement {
uint type; //0-4
bool touches_near;
bool touches_far;
uint original_index;
mat3x4 transform_inv;
vec3 scale;
uint pad;
};
layout(set = 0, binding = 2, std430) buffer restrict readonly RenderElements {
RenderElement data[];
}
render_elements;
void main() {
element_index = params.base_index + gl_InstanceIndex;
vec3 vertex = vertex_attrib;
vertex *= render_elements.data[element_index].scale;
vertex = vec4(vertex, 1.0) * render_elements.data[element_index].transform_inv;
depth_interp = -vertex.z;
gl_Position = state.projection * vec4(vertex, 1.0);
}
#[fragment]
#version 450
#VERSION_DEFINES
#if defined(has_GL_KHR_shader_subgroup_ballot) && defined(has_GL_KHR_shader_subgroup_arithmetic) && defined(has_GL_KHR_shader_subgroup_vote)
#extension GL_KHR_shader_subgroup_ballot : enable
#extension GL_KHR_shader_subgroup_arithmetic : enable
#extension GL_KHR_shader_subgroup_vote : enable
#define USE_SUBGROUPS
#endif
layout(location = 0) in float depth_interp;
layout(location = 1) in flat uint element_index;
layout(set = 0, binding = 1, std140) uniform State {
mat4 projection;
float inv_z_far;
uint screen_to_clusters_shift; // shift to obtain coordinates in block indices
uint cluster_screen_width; //
uint cluster_data_size; // how much data for a single cluster takes
uint cluster_depth_offset;
uint pad0;
uint pad1;
uint pad2;
}
state;
//cluster data is layout linearly, each cell contains the follow information:
// - list of bits for every element to mark as used, so (max_elem_count/32)*4 uints
// - a uint for each element to mark the depth bits used when rendering (0-31)
layout(set = 0, binding = 3, std430) buffer restrict ClusterRender {
uint data[];
}
cluster_render;
void main() {
//convert from screen to cluster
uvec2 cluster = uvec2(gl_FragCoord.xy) >> state.screen_to_clusters_shift;
//get linear cluster offset from screen poss
uint cluster_offset = cluster.x + state.cluster_screen_width * cluster.y;
//multiply by data size to position at the beginning of the element list for this cluster
cluster_offset *= state.cluster_data_size;
//find the current element in the list and plot the bit to mark it as used
uint usage_write_offset = cluster_offset + (element_index >> 5);
uint usage_write_bit = 1 << (element_index & 0x1F);
#ifdef USE_SUBGROUPS
uint cluster_thread_group_index;
if (!gl_HelperInvocation) {
//https://advances.realtimerendering.com/s2017/2017_Sig_Improved_Culling_final.pdf
uvec4 mask;
while (true) {
// find the cluster offset of the first active thread
// threads that did break; go inactive and no longer count
uint first = subgroupBroadcastFirst(cluster_offset);
// update the mask for thread that match this cluster
mask = subgroupBallot(first == cluster_offset);
if (first == cluster_offset) {
// This thread belongs to the group of threads that match this offset,
// so exit the loop.
break;
}
}
cluster_thread_group_index = subgroupBallotExclusiveBitCount(mask);
if (cluster_thread_group_index == 0) {
atomicOr(cluster_render.data[usage_write_offset], usage_write_bit);
}
}
#else
if (!gl_HelperInvocation) {
atomicOr(cluster_render.data[usage_write_offset], usage_write_bit);
}
#endif
//find the current element in the depth usage list and mark the current depth as used
float unit_depth = depth_interp * state.inv_z_far;
uint z_bit = clamp(uint(floor(unit_depth * 32.0)), 0, 31);
uint z_write_offset = cluster_offset + state.cluster_depth_offset + element_index;
uint z_write_bit = 1 << z_bit;
#ifdef USE_SUBGROUPS
if (!gl_HelperInvocation) {
z_write_bit = subgroupOr(z_write_bit); //merge all Zs
if (cluster_thread_group_index == 0) {
atomicOr(cluster_render.data[z_write_offset], z_write_bit);
}
}
#else
if (!gl_HelperInvocation) {
atomicOr(cluster_render.data[z_write_offset], z_write_bit);
}
#endif
}
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