92 lines
1.6 KiB
Plaintext
92 lines
1.6 KiB
Plaintext
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; Example PICA200 geometry shader
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; Uniforms
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.fvec projection[4]
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; Constants
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.constf myconst(0.0, 1.0, -1.0, 0.5)
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.alias zeros myconst.xxxx ; Vector full of zeros
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.alias ones myconst.yyyy ; Vector full of ones
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.alias half myconst.wwww
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; Outputs - this time the type *is* used
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.out outpos position
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.out outclr color
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; Inputs: we will receive the following inputs:
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; v0-v1: position/color of the first vertex
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; v2-v3: position/color of the second vertex
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; v4-v5: position/color of the third vertex
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.proc main
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; Calculate the midpoints of the vertices
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mov r4, v0
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add r4, v2, r4
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mul r4, half, r4
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mov r5, v2
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add r5, v4, r5
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mul r5, half, r5
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mov r6, v4
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add r6, v0, r6
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mul r6, half, r6
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; Emit the first triangle
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mov r0, v0
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mov r1, r4
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mov r2, r6
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call emit_triangle
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; Emit the second triangle
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mov r0, r4
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mov r1, v2
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mov r2, r5
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call emit_triangle
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; Emit the third triangle
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mov r0, r6
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mov r1, r5
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mov r2, v4
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call emit_triangle
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; We're finished
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end
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.end
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.proc emit_triangle
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; Emit the first vertex
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setemit 0
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mov r8, r0
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mov r9, v1
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call process_vertex
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emit
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; Emit the second vertex
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setemit 1
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mov r8, r1
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mov r9, v3
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call process_vertex
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emit
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; Emit the third vertex and finish the primitive
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setemit 2, prim
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mov r8, r2
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mov r9, v5
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call process_vertex
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emit
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.end
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; Subroutine
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; Inputs:
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; r8: vertex position
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; r9: vertex color
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.proc process_vertex
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; outpos = projectionMatrix * r8
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dp4 outpos.x, projection[0], r8
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dp4 outpos.y, projection[1], r8
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dp4 outpos.z, projection[2], r8
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dp4 outpos.w, projection[3], r8
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; outclr = r9
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mov outclr, r9
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.end
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