87 lines
2.5 KiB
GLSL
87 lines
2.5 KiB
GLSL
// tessellation control shader
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#version 450 core
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// specify number of control points per patch output
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// this value controls the size of the input and output arrays
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layout (vertices=4) out;
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layout(binding = 0) uniform uniform_per_frame
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{
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mat4 view;
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mat4 proj;
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vec3 viewer_pos;
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uint light_count;
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} ubo_per_frame;
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layout (location=0) in VS_OUT
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{
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vec2 vsUV;
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vec4 vsWorldPos;
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vec3 vsNormal;
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vec3 vsBiTangent;
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vec3 vsTangent;
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mat3 vsTBN;
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flat uint vsChunkID;
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flat uint vsMaterialID;
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}tc_in[];
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layout (location=0) out TC_OUT
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{
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vec2 vsUV;
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vec4 vsWorldPos;
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vec3 vsNormal;
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vec3 vsBiTangent;
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vec3 vsTangent;
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mat3 vsTBN;
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flat uint vsChunkID;
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flat uint vsMaterialID;
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}tc_out[];
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float inv_lerp (float a, float b, float t)
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{
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return (t - a) / (b - a);
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}
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void main()
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{
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// ----------------------------------------------------------------------
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// pass attributes through
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gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position;
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tc_out[gl_InvocationID].vsUV = tc_in[gl_InvocationID].vsUV;
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tc_out[gl_InvocationID].vsWorldPos = tc_in[gl_InvocationID].vsWorldPos;
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tc_out[gl_InvocationID].vsNormal = tc_in[gl_InvocationID].vsNormal;
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tc_out[gl_InvocationID].vsBiTangent = tc_in[gl_InvocationID].vsBiTangent;
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tc_out[gl_InvocationID].vsTangent = tc_in[gl_InvocationID].vsTangent;
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tc_out[gl_InvocationID].vsTBN = tc_in[gl_InvocationID].vsTBN;
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tc_out[gl_InvocationID].vsChunkID = tc_in[gl_InvocationID].vsChunkID;
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tc_out[gl_InvocationID].vsMaterialID = tc_in[gl_InvocationID].vsMaterialID;
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vec3 centre = (gl_in[0].gl_Position.xyz +
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gl_in[1].gl_Position.xyz +
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gl_in[2].gl_Position.xyz +
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gl_in[3].gl_Position.xyz) / 4.0;
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float patch_width = abs(length(gl_in[2].gl_Position.xyz - gl_in[0].gl_Position.xyz));
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float player_dist = abs(length(centre - ubo_per_frame.viewer_pos)) * 0.1;
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float tess_factor = 1.0 - inv_lerp(0, patch_width, player_dist);
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tess_factor = max(0.5, tess_factor);
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// ----------------------------------------------------------------------
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// invocation zero controls tessellation levels for the entire patch
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if (gl_InvocationID == 0)
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{
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float edgedivs = 32.0;
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float innerdivs = tess_factor * 64.0;
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gl_TessLevelOuter[0] = edgedivs;
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gl_TessLevelOuter[1] = edgedivs;
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gl_TessLevelOuter[2] = edgedivs;
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gl_TessLevelOuter[3] = edgedivs;
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gl_TessLevelInner[0] = innerdivs;
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gl_TessLevelInner[1] = innerdivs;
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}
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} |