141 lines
4.4 KiB
GLSL
141 lines
4.4 KiB
GLSL
/*
|
|
The MIT License (MIT)
|
|
|
|
Copyright (c) 2022 Sascha Willems
|
|
|
|
Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
of this software and associated documentation files (the "Software"), to deal
|
|
in the Software without restriction, including without limitation the rights
|
|
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
copies of the Software, and to permit persons to whom the Software is
|
|
furnished to do so, subject to the following conditions:
|
|
|
|
The above copyright notice and this permission notice shall be included in all
|
|
copies or substantial portions of the Software.
|
|
|
|
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
|
SOFTWARE.
|
|
*/
|
|
|
|
#version 450
|
|
|
|
layout(set = 0, binding = 0) uniform UBO
|
|
{
|
|
mat4 projection;
|
|
mat4 modelview;
|
|
vec4 lightPos;
|
|
vec4 frustumPlanes[6];
|
|
float displacementFactor;
|
|
float tessellationFactor;
|
|
vec2 viewportDim;
|
|
float tessellatedEdgeSize;
|
|
} ubo;
|
|
|
|
layout(set = 0, binding = 1) uniform sampler2D samplerHeight;
|
|
|
|
layout (vertices = 4) out;
|
|
|
|
layout (location = 0) in vec3 inNormal[];
|
|
layout (location = 1) in vec2 inUV[];
|
|
|
|
layout (location = 0) out vec3 outNormal[4];
|
|
layout (location = 1) out vec2 outUV[4];
|
|
|
|
// Calculate the tessellation factor based on screen space
|
|
// dimensions of the edge
|
|
float screenSpaceTessFactor(vec4 p0, vec4 p1)
|
|
{
|
|
// Calculate edge mid point
|
|
vec4 midPoint = 0.5 * (p0 + p1);
|
|
// Sphere radius as distance between the control points
|
|
float radius = distance(p0, p1) / 2.0;
|
|
|
|
// View space
|
|
vec4 v0 = ubo.modelview * midPoint;
|
|
|
|
// Project into clip space
|
|
vec4 clip0 = (ubo.projection * (v0 - vec4(radius, vec3(0.0))));
|
|
vec4 clip1 = (ubo.projection * (v0 + vec4(radius, vec3(0.0))));
|
|
|
|
// Get normalized device coordinates
|
|
clip0 /= clip0.w;
|
|
clip1 /= clip1.w;
|
|
|
|
// Convert to viewport coordinates
|
|
clip0.xy *= ubo.viewportDim;
|
|
clip1.xy *= ubo.viewportDim;
|
|
|
|
// Return the tessellation factor based on the screen size
|
|
// given by the distance of the two edge control points in screen space
|
|
// and a reference (min.) tessellation size for the edge set by the application
|
|
return clamp(distance(clip0, clip1) / ubo.tessellatedEdgeSize * ubo.tessellationFactor, 1.0, 64.0);
|
|
}
|
|
|
|
// Checks the current's patch visibility against the frustum using a sphere check
|
|
// Sphere radius is given by the patch size
|
|
bool frustumCheck()
|
|
{
|
|
// Fixed radius (increase if patch size is increased in example)
|
|
const float radius = 8.0f;
|
|
vec4 pos = gl_in[gl_InvocationID].gl_Position;
|
|
pos.y -= textureLod(samplerHeight, inUV[0], 0.0).r * ubo.displacementFactor;
|
|
|
|
// Check sphere against frustum planes
|
|
for (int i = 0; i < 6; i++) {
|
|
if (dot(pos, ubo.frustumPlanes[i]) + radius < 0.0)
|
|
{
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
void main()
|
|
{
|
|
if (gl_InvocationID == 0)
|
|
{
|
|
if (!frustumCheck())
|
|
{
|
|
gl_TessLevelInner[0] = 0.0;
|
|
gl_TessLevelInner[1] = 0.0;
|
|
gl_TessLevelOuter[0] = 0.0;
|
|
gl_TessLevelOuter[1] = 0.0;
|
|
gl_TessLevelOuter[2] = 0.0;
|
|
gl_TessLevelOuter[3] = 0.0;
|
|
}
|
|
else
|
|
{
|
|
if (ubo.tessellationFactor > 0.0)
|
|
{
|
|
gl_TessLevelOuter[0] = screenSpaceTessFactor(gl_in[3].gl_Position, gl_in[0].gl_Position);
|
|
gl_TessLevelOuter[1] = screenSpaceTessFactor(gl_in[0].gl_Position, gl_in[1].gl_Position);
|
|
gl_TessLevelOuter[2] = screenSpaceTessFactor(gl_in[1].gl_Position, gl_in[2].gl_Position);
|
|
gl_TessLevelOuter[3] = screenSpaceTessFactor(gl_in[2].gl_Position, gl_in[3].gl_Position);
|
|
gl_TessLevelInner[0] = mix(gl_TessLevelOuter[0], gl_TessLevelOuter[3], 0.5);
|
|
gl_TessLevelInner[1] = mix(gl_TessLevelOuter[2], gl_TessLevelOuter[1], 0.5);
|
|
}
|
|
else
|
|
{
|
|
// Tessellation factor can be set to zero by example
|
|
// to demonstrate a simple passthrough
|
|
gl_TessLevelInner[0] = 1.0;
|
|
gl_TessLevelInner[1] = 1.0;
|
|
gl_TessLevelOuter[0] = 1.0;
|
|
gl_TessLevelOuter[1] = 1.0;
|
|
gl_TessLevelOuter[2] = 1.0;
|
|
gl_TessLevelOuter[3] = 1.0;
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position;
|
|
outNormal[gl_InvocationID] = inNormal[gl_InvocationID];
|
|
outUV[gl_InvocationID] = inUV[gl_InvocationID];
|
|
}
|