89 lines
2.4 KiB
GLSL
89 lines
2.4 KiB
GLSL
#version 450 core
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#extension GL_EXT_debug_printf : enable
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layout (set = 0, binding = 0) uniform Matrices {
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mat4 view;
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mat4 proj;
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float time;
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vec3 cam_pos;
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vec3 cam_dir;
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vec4 frustum[6];
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vec2 viewport;
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float tess_factor;
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float tess_edge_size;
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};
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layout(set = 0, binding = 1) uniform sampler2D heightmap;
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layout (vertices = 4) out;
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layout (location = 0) in vec3 norm[];
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layout (location = 1) in vec2 texCoord[];
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layout (location = 2) in vec3 pos[];
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layout (location = 0) out vec3 _norm[4];
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layout (location = 1) out vec2 _texCoord[4];
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layout (location = 2) out vec3 _pos[4];
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float screen_space_tess(vec4 p0, vec4 p1) {
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/* calc midpoint + distance btw the two points */
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vec4 midp = 0.5*(p0+p1);
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float r = distance(p0, p1) / 2.0;
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vec4 v0 = view * midp;
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/* project into clip spaace */
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vec4 clip0 = proj * (v0 - vec4(r, vec3(0.0)));
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vec4 clip1 = proj * (v0 + vec4(r, vec3(0.0)));
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clip0 /= clip0.w;
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clip1 /= clip1.w;
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/* convert to viewport coords */
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clip0.xy *= viewport;
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clip1.xy *= viewport;
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return clamp(distance(clip0, clip1) / tess_edge_size * tess_factor, 1.0, 64.0);
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}
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bool frustum_culling() {
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/* square root of patch size */
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const float r = 8.0f;
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/* ensure this is consistent with tese shader */
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vec4 fpos = gl_in[gl_InvocationID].gl_Position;
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fpos.y += 15.0 * textureLod(heightmap, texCoord[0], 0.0).r;
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for(int i = 0; i < 6; i++) {
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if(dot(fpos, frustum[i]) + r < 0.0)
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return false;
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}
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return true;
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}
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void main() {
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if(gl_InvocationID == 0) {
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/* perform frustum culling */
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if(frustum_culling()) {
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gl_TessLevelOuter[0] = screen_space_tess(gl_in[3].gl_Position, gl_in[0].gl_Position);
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gl_TessLevelOuter[1] = screen_space_tess(gl_in[0].gl_Position, gl_in[1].gl_Position);
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gl_TessLevelOuter[2] = screen_space_tess(gl_in[1].gl_Position, gl_in[2].gl_Position);
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gl_TessLevelOuter[3] = screen_space_tess(gl_in[2].gl_Position, gl_in[3].gl_Position);
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gl_TessLevelInner[0] = mix(gl_TessLevelOuter[0], gl_TessLevelOuter[3], 0.5);
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gl_TessLevelInner[1] = mix(gl_TessLevelOuter[2], gl_TessLevelOuter[1], 0.5);
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} else {
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gl_TessLevelOuter[0] = 0.0;
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gl_TessLevelOuter[1] = 0.0;
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gl_TessLevelOuter[2] = 0.0;
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gl_TessLevelOuter[3] = 0.0;
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gl_TessLevelInner[0] = 0.0;
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gl_TessLevelInner[1] = 0.0;
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}
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}
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gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position;
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_norm[gl_InvocationID] = norm[gl_InvocationID];
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_texCoord[gl_InvocationID] = texCoord[gl_InvocationID];
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_pos[gl_InvocationID] = pos[gl_InvocationID];
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} |