mirror of
https://github.com/aap/librw.git
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40 lines
1.8 KiB
Plaintext
40 lines
1.8 KiB
Plaintext
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/* This is the the projection matrix we start with:
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* 1/2w 0 ox/2w + 1/2 -ox/2w
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* 0 -1/2h -oy/2h + 1/2 oy/2h
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* 0 0 1 0
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* 0 0 1 0
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* To get rid of the +1/2 in the combined matrix we
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* subtract the z-row/2 from the x- and y-rows.
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*
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* The z-row is then set to [0 0 0 1] such that multiplication
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* by XYZscale gives [0 0 0 zScale]. After perspective division
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* and addition of XYZoffset we then get zScale/w + zShift for z.
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*
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* XYZScale scales xy to the resolution and z by zScale.
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* XYZOffset translates xy to the GS coordinate system (where
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* [2048, 2048] is the center of the frame buffer) and add zShift to z.
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*/
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; constant:
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; VF28-VF31 transformation matrix
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; VF25 XYZ offset
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SUB.z VF28, VF28, VF28 LOI 0.5 ; right.z = 0
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SUB.z VF29, VF29, VF29 LQ VF28, matrix(VI00) ; up.z = 0 - load matrix
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SUB.z VF30, VF30, VF30 LQ VF29, matrix+1(VI00) ; at.z = 0 - load matrix
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ADDw.z VF31, VF00, VF00 LQ VF30, matrix+2(VI00) ; at.z = 1 - load matrix
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NOP LQ VF31, matrix+3(VI00) ; - load matrix
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MULi.w VF20, VF28, I LQ.xyz VF01, XYZScale(VI00) ; fix matrix - load scale
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MULi.w VF21, VF29, I NOP ; fix matrix
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MULi.w VF22, VF30, I NOP ; fix matrix
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MULi.w VF23, VF31, I NOP ; fix matrix
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SUBw.xy VF28, VF28, VF20 NOP ; fix matrix
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SUBw.xy VF29, VF29, VF21 NOP ; fix matrix
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SUBw.xy VF30, VF30, VF22 NOP ; fix matrix
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SUBw.xy VF31, VF31, VF23 NOP ; fix matrix
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MUL.xy VF28, VF28, VF01 LQ.xyz VF25, XYZOffset(VI00) ; scale matrix
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MUL.xy VF29, VF29, VF01 IADDIU VI12, VI00, outBuf1 ; scale matrix
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MUL.xy VF30, VF30, VF01 IADDIU VI13, VI00, outBuf2 ; scale matrix
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MUL.xyz VF31, VF31, VF01 NOP ; scale matrix
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