themes/src/shaders/grass_vert.cpp


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#include "grass_vert.h"

const char* shader_grass_vert = "attribute vec2 position;        // Local quad vertex: x in [-0.5, 0.5], y in [0, 1] \n"
"attribute vec3 instancePos;     // Per-instance: world-space base of blade \n"
"attribute float instancePhase;  // Per-instance: random phase offset for sway \n"
"attribute float instanceHeight; // Per-instance: height scale multiplier \n"
" \n"
"uniform mat4 projection; \n"
"uniform mat4 view; \n"
"uniform float time; \n"
"uniform float bladeWidth; \n"
"uniform float bladeHeight; \n"
"uniform float swayAmount; \n"
" \n"
"varying lowp vec2 vUV; \n"
" \n"
"void main() { \n"
"    vec3 cameraRight = vec3(view[0][0], view[1][0], view[2][0]); \n"
"    float h = bladeHeight * instanceHeight; \n"
"    float sway = sin(time * 1.5 + instancePhase) * swayAmount * position.y; \n"
"    vec3 worldPos = instancePos \n"
"                  + cameraRight * (position.x + sway) * bladeWidth \n"
"                  + vec3(0.0, 1.0, 0.0) * position.y * h; \n"
" \n"
"    gl_Position = projection * view * vec4(worldPos, 1.0); \n"
"    vUV = vec2(position.x + 0.5, position.y); \n"
"} \n"
" \n";