gg/shader.go

package gg

import (
	"github.com/hajimehoshi/ebiten/v2"
	//"fmt"
)

type Shader = ebiten.Shader
type ShaderOptions struct {
	Shader *Shader
	Uniforms map[string] any
	Images [4]*Image
}

var (
	// The shader is for example only.
	SolidWhiteColorShader = MustNewShader([]byte(`
		package main
		
		//var Random float
		
		func Fragment(dst vec4,  src vec2, _ vec4) vec4 {
			c := imageSrc0UnsafeAt(src)
			size := imageSrc0Size()
			//ret := vec4(0.1) * src.x/size.x
			//ret := c * src.x/size.x
			//ret.r = 1
			//ret.a = c.a
			//c.a = 0
			//c.rg = vec2(0)
			//c.a = c.b
			//ret := vec4(1, 1, 1, 0)
			//ret.a /= 5
			//ret.a = src.x
			//c.a /= 5
			//c = vec4(c.a)
			orig := imageSrc0Origin()
			src -= orig
			c.a *= (size.x-src.x)/size.x
			return c
		}
	`))
)

func MustNewShader(src []byte) (*Shader) {
	shader, err := NewShader(src)
	if err != nil {
		panic(err)
	}
	
	return shader
}

func NewShader(src []byte) (*Shader, error) {
	return ebiten.NewShader(src)
}