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// Instanced snowflake vertex shader
attribute vec2 position; // Base quad vertex position
attribute vec2 instancePos; // Per-instance: snowflake center position
attribute float instanceRot; // Per-instance: rotation angle
attribute float instanceScale; // Per-instance: size scale
attribute float instanceSeed; // Per-instance: random seed for variation
uniform mat4 projection;
uniform mat4 model;
varying lowp vec2 vUV; // UV coordinates for fragment shader
varying lowp float vSeed; // Pass seed to fragment shader
varying lowp float vScale; // Pass scale to fragment shader
void main() {
// Rotate and scale the base quad
float c = cos(instanceRot);
float s = sin(instanceRot);
mat2 rotation = mat2(c, s, -s, c);
vec2 rotatedPos = rotation * (position * instanceScale);
vec2 worldPos = instancePos + rotatedPos;
gl_Position = projection * model * vec4(worldPos, 0.0, 1.0);
// Pass UV in range [-1, 1] for procedural generation
vUV = position;
vSeed = instanceSeed;
vScale = instanceScale;
}
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