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Downloads
Demos:
geexlab-demopack-mesh-shaders/gl/textured-quad/ geexlab-demopack-mesh-shaders/vk/textured-quad/ |
Rendering a textured quad with mesh shaders follows the same principle than for a RGB triangle:
– RGB Triangle with Mesh Shaders in OpenGL
– RGB Triangle with Mesh Shaders in Vulkan).
Ok there is an additional vertex and a texture, but it’s very very similar.
Here is the mesh shader, which is almost identical in OpenGL and Vulkan (in Vulkan there is an extra transformation: pos.y = -pos.y; pos.z = (pos.z + pos.w) / 2.0 for each vertex):
#version 450 #extension GL_NV_mesh_shader : require layout(local_size_x = 1) in; layout(triangles, max_vertices = 4, max_primitives = 2) out; // Custom vertex output block layout (location = 0) out PerVertexData { vec4 color; vec4 uv; } v_out[]; // [max_vertices] float scale = 0.95; const vec3 vertices[4] = { vec3(-1,-1,0), vec3(-1,1,0), vec3(1,1,0), vec3(1,-1,0) }; const vec3 colors[4] = { vec3(1.0,0.0,0.0), vec3(0.0,1.0,0.0), vec3(0.0,0.0,1.0), vec3(1.0,0.0,1.0) }; const vec2 uvs[4] = { vec2(0.0,0.0), vec2(0.0,1.0), vec2(1.0,1.0), vec2(1.0,0.0) }; void main() { vec4 pos = vec4(vertices[0]*scale, 1.0); // GL->VK conventions... pos.y = -pos.y; pos.z = (pos.z + pos.w) / 2.0; gl_MeshVerticesNV[0].gl_Position = pos; pos = vec4(vertices[1] * scale, 1.0); pos.y = -pos.y; pos.z = (pos.z + pos.w) / 2.0; gl_MeshVerticesNV[1].gl_Position = pos; pos = vec4(vertices[2] * scale, 1.0); pos.y = -pos.y; pos.z = (pos.z + pos.w) / 2.0; gl_MeshVerticesNV[2].gl_Position = pos; pos = vec4(vertices[3] * scale, 1.0); pos.y = -pos.y; pos.z = (pos.z + pos.w) / 2.0; gl_MeshVerticesNV[3].gl_Position = pos; v_out[0].color = vec4(colors[0], 1.0); v_out[1].color = vec4(colors[1], 1.0); v_out[2].color = vec4(colors[2], 1.0); v_out[3].color = vec4(colors[3], 1.0); v_out[0].uv = vec4(uvs[0], 0, 1); v_out[1].uv = vec4(uvs[1], 0, 1); v_out[2].uv = vec4(uvs[2], 0, 1); v_out[3].uv = vec4(uvs[3], 0, 1); gl_PrimitiveIndicesNV[0] = 0; gl_PrimitiveIndicesNV[1] = 1; gl_PrimitiveIndicesNV[2] = 2; gl_PrimitiveIndicesNV[3] = 2; gl_PrimitiveIndicesNV[4] = 3; gl_PrimitiveIndicesNV[5] = 0; gl_PrimitiveCountNV = 2; } |
And here is the pixel shader, for both APIs:
#version 450 layout (location = 0) in PerVertexData { vec4 color; vec4 uv; } fragIn; layout (binding = 0) uniform sampler2D tex0; layout (location = 0) out vec4 FragColor; void main() { vec2 uv = fragIn.uv.xy; uv.y *= -1.0; vec4 t = texture(tex0, uv); FragColor = fragIn.color * t; } |
In the Lua side, the code is nearly similar, the little difference is the texture: in OpenGL the texture has to be bound before rendering while in Vulkan the texture is a resource added to the descriptor set used by the pipeline.
The drawing code in the OpenGL demo:
gh_texture.bind(tex, 0) gh_gpu_program.bind(nv_mesh_prog) gh_renderer.draw_mesh_tasks(0, 1) |
OpenGL demo:
The drawing code in the Vulkan demo:
gh_vk.descriptorset_bind(ds) gh_vk.pipeline_bind(mesh_pipeline) gh_vk.draw_mesh_tasks(0, 1) |
Vulkan demo:
