TessellationExample(void)
: shape_instr(make_shape.Instructions(PrimitiveType::Patches))
, shape_indices(make_shape.Indices())
, vs(ObjectDesc("Vertex"))
, cs(ObjectDesc("Tessellation Control"))
, es(ObjectDesc("Tessellation Evaluation"))
, gs(ObjectDesc("Geometry"))
, fs(ObjectDesc("Fragment"))
, projection_matrix(prog, "ProjectionMatrix")
, camera_matrix(prog, "CameraMatrix")
, model_matrix(prog, "ModelMatrix")
, offset(prog, "Offset")
, view_position(prog, "ViewPosition")
, viewport_dimensions(prog, "ViewportDimensions")
{
vs.Source(
"#version 410\n"
"uniform vec3 ViewPosition;"
"in vec3 Position;"
"out vec3 vertPosition;"
"out float vertDistance;"
"void main(void)"
"{"
" vertPosition = Position;"
" vertDistance = length(ViewPosition - vertPosition);"
"}"
);
vs.Compile();
cs.Source(
"#version 410\n"
"layout(vertices = 3) out;"
"in vec3 vertPosition[];"
"in float vertDistance[];"
"out vec3 tecoPosition[];"
"int tessLevel(float dist)"
"{"
" return int(9.0 / sqrt(dist+0.1));"
"}"
"void main(void)"
"{"
" tecoPosition[gl_InvocationID] ="
" vertPosition[gl_InvocationID];"
" if(gl_InvocationID == 0)"
" {"
" gl_TessLevelInner[0] = tessLevel(("
" vertDistance[0]+"
" vertDistance[1]+"
" vertDistance[2] "
" )*0.333);"
" gl_TessLevelOuter[0] = tessLevel(("
" vertDistance[1]+"
" vertDistance[2] "
" )*0.5);"
" gl_TessLevelOuter[1] = tessLevel(("
" vertDistance[2]+"
" vertDistance[0] "
" )*0.5);"
" gl_TessLevelOuter[2] = tessLevel(("
" vertDistance[0]+"
" vertDistance[1] "
" )*0.5);"
" }"
"}"
);
cs.Compile();
es.Source(
"#version 410\n"
"layout(triangles, equal_spacing, ccw) in;"
"const vec3 LightPosition = vec3(12.0, 10.0, 7.0);"
"uniform mat4 ProjectionMatrix, CameraMatrix, ModelMatrix;"
"in vec3 tecoPosition[];"
"out vec3 teevNormal;"
"out vec3 teevLightDir;"
"void main(void)"
"{"
" vec3 p0 = gl_TessCoord.x * tecoPosition[0];"
" vec3 p1 = gl_TessCoord.y * tecoPosition[1];"
" vec3 p2 = gl_TessCoord.z * tecoPosition[2];"
" vec4 tempPosition = vec4(normalize(p0+p1+p2), 0.0);"
" teevNormal = (ModelMatrix * tempPosition).xyz;"
" tempPosition.w = 1.0;"
" tempPosition = ModelMatrix * tempPosition;"
" teevLightDir = LightPosition - tempPosition.xyz;"
" gl_Position = "
" ProjectionMatrix *"
" CameraMatrix *"
" tempPosition;"
"}"
);
es.Compile();
gs.Source(
"#version 410\n"
"layout (triangles) in;"
"layout (triangle_strip, max_vertices = 3) out;"
"uniform vec3 Offset;"
"uniform vec2 ViewportDimensions;"
"in vec3 teevNormal[], teevLightDir[];"
"noperspective out vec3 geomDist;"
"flat out vec3 geomNormal;"
"out vec3 geomColor;"
"out vec3 geomLightDir;"
"void main(void)"
"{"
" geomNormal = normalize("
" teevNormal[0]+"
" teevNormal[1]+"
" teevNormal[2]"
" );"
" vec2 ScreenPos[3];"
" for(int i=0; i!=3; ++i)"
" {"
" ScreenPos[i] = "
" ViewportDimensions*"
" gl_in[i].gl_Position.xy/"
" gl_in[i].gl_Position.w;"
" }"
" vec2 TmpVect[3];"
" for(int i=0; i!=3; ++i)"
" {"
" TmpVect[i] = "
" ScreenPos[(i+2)%3]-"
" ScreenPos[(i+1)%3];"
" }"
" const vec3 EdgeMask[3] = vec3[3]("
" vec3(1.0, 0.0, 0.0),"
" vec3(0.0, 1.0, 0.0),"
" vec3(0.0, 0.0, 1.0) "
" );"
" for(int i=0; i!=3; ++i)"
" {"
" float Dist = abs("
" TmpVect[(i+1)%3].x*TmpVect[(i+2)%3].y-"
" TmpVect[(i+1)%3].y*TmpVect[(i+2)%3].x "
" ) / length(TmpVect[i]);"
" vec3 DistVect = vec3(Dist, Dist, Dist);"
" gl_Position = gl_in[i].gl_Position;"
" geomColor = normalize(abs("
" vec3(2.0, 2.0, 2.0)-"
" teevNormal[i]-"
" Offset"
" ));"
" geomLightDir = teevLightDir[i];"
" geomDist = EdgeMask[i] * DistVect;"
" EmitVertex();"
" }"
" EndPrimitive();"
"}"
);
gs.Compile();
fs.Source(
"#version 410\n"
"noperspective in vec3 geomDist;"
"flat in vec3 geomNormal;"
"in vec3 geomColor;"
"in vec3 geomLightDir;"
"out vec3 fragColor;"
"void main(void)"
"{"
" float MinDist = min(min(geomDist.x,geomDist.y),geomDist.z);"
" float EdgeAlpha = exp2(-pow(MinDist, 2.0));"
" const float Ambient = 0.8;"
" float Diffuse = max(dot("
" normalize(geomNormal),"
" normalize(geomLightDir)"
" ), 0.0);"
" vec3 FaceColor = geomColor * (Diffuse + Ambient);"
" const vec3 EdgeColor = vec3(0.0, 0.0, 0.0);"
" fragColor = mix(FaceColor, EdgeColor, EdgeAlpha);"
"}"
);
fs.Compile();
prog.AttachShader(vs);
prog.AttachShader(cs);
prog.AttachShader(es);
prog.AttachShader(gs);
prog.AttachShader(fs);
prog.Link();
prog.Use();
shape.Bind();
verts.Bind(Buffer::Target::Array);
{
std::vector<GLfloat> data;
GLuint n_per_vertex = make_shape.Positions(data);
Buffer::Data(Buffer::Target::Array, data);
VertexAttribArray attr(prog, "Position");
attr.Setup(n_per_vertex, DataType::Float);
attr.Enable();
indices.Bind(Buffer::Target::ElementArray);
Buffer::Data(Buffer::Target::ElementArray, shape_indices);
shape_indices.clear();
}
//
gl.ClearColor(0.8f, 0.8f, 0.8f, 0.0f);
gl.ClearDepth(1.0f);
gl.Enable(Capability::DepthTest);
prog.Use();
}
