116 строки
3.2 KiB
GLSL
116 строки
3.2 KiB
GLSL
#version 310 es
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#extension GL_EXT_tessellation_shader : require
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layout(vertices = 1) out;
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in vec2 vPatchPosBase[];
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layout(std140) uniform UBO
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{
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vec4 uScale;
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highp vec3 uCamPos;
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vec2 uPatchSize;
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vec2 uMaxTessLevel;
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float uDistanceMod;
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vec4 uFrustum[6];
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};
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patch out vec2 vOutPatchPosBase;
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patch out vec4 vPatchLods;
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float lod_factor(vec2 pos_)
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{
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vec2 pos = pos_ * uScale.xy;
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vec3 dist_to_cam = uCamPos - vec3(pos.x, 0.0, pos.y);
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float level = log2((length(dist_to_cam) + 0.0001) * uDistanceMod);
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return clamp(level, 0.0, uMaxTessLevel.x);
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}
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float tess_level(float lod)
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{
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return uMaxTessLevel.y * exp2(-lod);
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}
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vec4 tess_level(vec4 lod)
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{
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return uMaxTessLevel.y * exp2(-lod);
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}
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// Guard band for vertex displacement.
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#define GUARD_BAND 10.0
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bool frustum_cull(vec2 p0)
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{
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vec2 min_xz = (p0 - GUARD_BAND) * uScale.xy;
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vec2 max_xz = (p0 + uPatchSize + GUARD_BAND) * uScale.xy;
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vec3 bb_min = vec3(min_xz.x, -GUARD_BAND, min_xz.y);
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vec3 bb_max = vec3(max_xz.x, +GUARD_BAND, max_xz.y);
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vec3 center = 0.5 * (bb_min + bb_max);
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float radius = 0.5 * length(bb_max - bb_min);
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vec3 f0 = vec3(
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dot(uFrustum[0], vec4(center, 1.0)),
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dot(uFrustum[1], vec4(center, 1.0)),
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dot(uFrustum[2], vec4(center, 1.0)));
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vec3 f1 = vec3(
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dot(uFrustum[3], vec4(center, 1.0)),
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dot(uFrustum[4], vec4(center, 1.0)),
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dot(uFrustum[5], vec4(center, 1.0)));
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return !(any(lessThanEqual(f0, vec3(-radius))) || any(lessThanEqual(f1, vec3(-radius))));
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}
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void compute_tess_levels(vec2 p0)
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{
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vOutPatchPosBase = p0;
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float l00 = lod_factor(p0 + vec2(-0.5, -0.5) * uPatchSize);
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float l10 = lod_factor(p0 + vec2(+0.5, -0.5) * uPatchSize);
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float l20 = lod_factor(p0 + vec2(+1.5, -0.5) * uPatchSize);
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float l01 = lod_factor(p0 + vec2(-0.5, +0.5) * uPatchSize);
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float l11 = lod_factor(p0 + vec2(+0.5, +0.5) * uPatchSize);
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float l21 = lod_factor(p0 + vec2(+1.5, +0.5) * uPatchSize);
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float l02 = lod_factor(p0 + vec2(-0.5, +1.5) * uPatchSize);
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float l12 = lod_factor(p0 + vec2(+0.5, +1.5) * uPatchSize);
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float l22 = lod_factor(p0 + vec2(+1.5, +1.5) * uPatchSize);
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vec4 lods = vec4(
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dot(vec4(l01, l11, l02, l12), vec4(0.25)),
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dot(vec4(l00, l10, l01, l11), vec4(0.25)),
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dot(vec4(l10, l20, l11, l21), vec4(0.25)),
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dot(vec4(l11, l21, l12, l22), vec4(0.25)));
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vPatchLods = lods;
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vec4 outer_lods = min(lods.xyzw, lods.yzwx);
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vec4 levels = tess_level(outer_lods);
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gl_TessLevelOuter[0] = levels.x;
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gl_TessLevelOuter[1] = levels.y;
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gl_TessLevelOuter[2] = levels.z;
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gl_TessLevelOuter[3] = levels.w;
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float min_lod = min(min(lods.x, lods.y), min(lods.z, lods.w));
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float inner = tess_level(min(min_lod, l11));
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gl_TessLevelInner[0] = inner;
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gl_TessLevelInner[1] = inner;
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}
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void main()
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{
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vec2 p0 = vPatchPosBase[0];
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if (!frustum_cull(p0))
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{
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gl_TessLevelOuter[0] = -1.0;
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gl_TessLevelOuter[1] = -1.0;
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gl_TessLevelOuter[2] = -1.0;
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gl_TessLevelOuter[3] = -1.0;
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gl_TessLevelInner[0] = -1.0;
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gl_TessLevelInner[1] = -1.0;
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}
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else
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{
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compute_tess_levels(p0);
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}
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}
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