![]() It does this for various reasons, for example when part of a triangle ends up clipped. The GPU is capable of splitting up triangles fed to it for rendering. This makes it possible to add more details to geometry, though in this tutorial we'll focus on the tessellation process itself. In our case, we're going to subdivide triangles so we end up with smaller triangles that cover the same space. Tessellation is the art of cutting things into smaller parts. If you don't have enough triangles, make some more. This tutorial is made with Unity 2017.1.0. It uses the Flat and Wireframe Shading tutorial as a basis. Vec3 map = texture(tex_normal, texcoord ).This tutorial covers how to add support for tessellation to a custom shader. assume N, the interpolated vertex normal and Vec3 perturb_normal(vec3 N, vec3 V, vec2 texcoord) Return mat3( T * invmax, B * invmax, N ) Vec3 B = dp2perp * duv1.y + dp1perp * duv2.y įloat invmax = inversesqrt( max( dot(T,T), dot(B,B) ) ) Vec3 T = dp2perp * duv1.x + dp1perp * duv2.x get edge vectors of the pixel triangle Mat3 cotangent_frame(vec3 N, vec3 p, vec2 uv) Gl_Position = gxl3d_ProjectionMatrix * view_pos Vec4 lp = gxl3d_ViewMatrix * light_position Vec4 view_pos = modelview * vec4(finalPos,1.0) Tes_normal = modelview * vec4(Normal, 0.0) Mat4 modelview = gxl3d_ViewMatrix * gxl3d_ModelMatrix Vec3 finalPos = tess_alpha*pnPos + (1.0-tess_alpha)*barPos Vec3 pnPos = gl_in.gl_Position.xyz*uvwCubed Vec3 barPos = gl_TessCoord*gl_in.gl_Position.xyz + gl_TessCoord*gl_in.gl_Position.xyz + gl_TessCoord*gl_in.gl_Position.xyz Vec3 Normal = normalize(tess_alpha*pnNormal + (1.0-tess_alpha) * barNormal) Vec3 pnNormal = tcs_normal.xyz*uvwSquared + tcs_normal.xyz*uvwSquared + tcs_normal.xyz*uvwSquared ![]() Vec3 barNormal = gl_TessCoord*tcs_normal.xyz + gl_TessCoord*tcs_normal.xyz + gl_TessCoord*tcs_normal.xyz Vec4 uv = (gl_TessCoord*tcs_uv + gl_TessCoord*tcs_uv + gl_TessCoord*tcs_uv) * uv_tiling Layout(triangles, fractional_even_spacing, ccw) in Tcs_uv = v_uv įloat P0 = gl_in.gl_Position įloat P1 = gl_in.gl_Position įloat P2 = gl_in.gl_Position ![]() Return 2.0*dot(Pj_minus_Pi, Ni_plus_Nj) / dot(Pj_minus_Pi, Pj_minus_Pi) Vec3 Ni_plus_Nj = v_normal.xyz + v_normal.xyz Vec3 Pj_minus_Pi = gl_in.gl_Position.xyz - gl_in.gl_Position.xyz Return dot(gl_in.gl_Position.xyz - gl_in.gl_Position.xyz, v_normal.xyz) #extension GL_EXT_tessellation_shader : require Here is complete GPU program for Tinker Board / OpenGL ES 3.1: – Windows 10 + GeForce GTX 1070: 3300 FPS – Tinker Board with Mali T760 GPU: 30 FPS On Tinker Board, same thing than on Linux: edit the demo.sh and run demo.sh with sh. ![]() Then run the demo.sh in command line: sh. On Linux, edit the demo.sh file with the path to the demo.On Windows and macOS, start GeeXLab and drag/drop the demo into GeeXLab.For Tinker Board users, the demo is shipped with GeeXLab for Tinker Board GLES and is available in the demos/tessellation/ folder (demo03.xml). The rest of the demo is a simple mesh sphere rendered with a tessellation GPU program.įor desktops (Windows, Linux and macOS), you can find the in the gl-40/tessellation_demo/ folder of the full code sample pack. I found this pixel shader in the Mali OpenGL ES SDK. All parts of the environment are generated by the pixel shader. This demo is cool because the whole environment (the sky, the ground as well as the shadow on the ground) is in reality a simple quad rendered with a pixel shader. I also ported this demo to OpenGL 4.0 (Windows, Linux and macOS). For the release of GeeXLab 0.20.1, I coded a small tessellation demo for the Tinker Board (OpenGL ES 3.1).
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