;
;	Command & Conquer Generals Zero Hour(tm)
;	Copyright 2025 Electronic Arts Inc.
;
;	This program is free software: you can redistribute it and/or modify
;	it under the terms of the GNU General Public License as published by
;	the Free Software Foundation, either version 3 of the License, or
;	(at your option) any later version.
;
;	This program is distributed in the hope that it will be useful,
;	but WITHOUT ANY WARRANTY; without even the implied warranty of
;	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;	GNU General Public License for more details.
;
;	You should have received a copy of the GNU General Public License
;	along with this program.  If not, see <http://www.gnu.org/licenses/>.
;

//vertex shader for grass..
// v0   - Vertex Position
// v1   - Normal vector - used for other fun stuff.
//      - v1.x = index for the motion wave data 
//      - v1.y = color scale factor for darkening.
//      - v1.z = z coordinate value of the base of the tree/grass/bush.
// v2   - Diffuse color
// v7   - Vertex Texture Data u,v 
// c4-7  - Composite World-View-Projection Matrix
// c8  - Tilt vector.
// c32  - offset for shroud texture mapping
// c33  - scale for shroud texture mapping

vs.1.1


mov  r2, v1.wwzw    ; move the z value for the tree into r2
sub  r2, v0, r2     ; subtract the z from the base coordinate.
mov  a0.x, v1       ; get the index for the wave value.
mov  r0, c[a0.x+8]  ; load the correct wave entry for this tree/grass
mad  r1, r2.zzzw,r0,v0 ; multiply the z value by wave value to get the xy skew value for the wave motion
                    ; and add it to the coordinate value.
m4x4 oPos, r1, c4   ; Transform vertex to screen coords.
mov  r2, v1.yyyw    ; Get the color scale from v1.y
mul  oD0, v2,r2 	  ; Scale and move diffuse color into color register.
mov  oT0, v7			  ; Move texture coords into texture register.

add  r1, v0, c32    ; offset coordinate
mul  oT1, r1, c33    ;