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package pixelgl
import (
"github.com/faiface/glhf"
"github.com/faiface/mainthread"
"github.com/go-gl/mathgl/mgl32"
"github.com/pkg/errors"
)
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// glShader is a type to assist with managing a canvas's underlying
// shader configuration. This allows for customization of shaders on
// a per canvas basis.
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type glShader struct {
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s *glhf.Shader
vf, uf glhf.AttrFormat
vs, fs string
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uniforms []gsUniformAttr
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uniformDefaults struct {
transform mgl32.Mat3
colormask mgl32.Vec4
bounds mgl32.Vec4
texbounds mgl32.Vec4
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}
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type gsUniformAttr struct {
Name string
Type glhf.AttrType
value interface{}
ispointer bool
}
// reinitialize GLShader data and recompile the underlying gl shader object
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func (gs *glShader) update() {
gs.uf = nil
for _, u := range gs.uniforms {
gs.uf = append(gs.uf, glhf.Attr{
Name: u.Name,
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Type: u.Type,
})
}
var shader *glhf.Shader
mainthread.Call(func() {
var err error
shader, err = glhf.NewShader(
gs.vf,
gs.uf,
gs.vs,
gs.fs,
)
if err != nil {
panic(errors.Wrap(err, "failed to create Canvas, there's a bug in the shader"))
}
})
gs.s = shader
}
// gets the uniform index from GLShader
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func (gs *glShader) getUniform(Name string) int {
for i, u := range gs.uniforms {
if u.Name == Name {
return i
}
}
return -1
}
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// SetUniform appends a custom uniform name and value to the shader.
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// if the uniform already exists, it will simply be overwritten.
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// example:
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// utime := float32(time.Since(starttime)).Seconds())
// mycanvas.shader.AddUniform("u_time", &utime)
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func (gs *glShader) setUniform(name string, value interface{}) {
t, p := getAttrType(value)
if loc := gs.getUniform(name); loc > -1 {
gs.uniforms[loc].Name = name
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gs.uniforms[loc].Type = t
gs.uniforms[loc].ispointer = p
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gs.uniforms[loc].value = value
return
}
gs.uniforms = append(gs.uniforms, gsUniformAttr{
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Name: name,
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Type: t,
ispointer: p,
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value: value,
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// Sets up a base shader with everything needed for a Pixel
// canvas to render correctly. The defaults can be overridden
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// by simply using the SetUniform function.
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gs := &glShader{
fs: baseCanvasFragmentShader,
}
gs.setUniform("uTransform", &gs.uniformDefaults.transform)
gs.setUniform("uColorMask", &gs.uniformDefaults.colormask)
gs.setUniform("uBounds", &gs.uniformDefaults.bounds)
gs.setUniform("uTexBounds", &gs.uniformDefaults.texbounds)
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// Value returns the attribute's concrete value. If the stored value
// is a pointer, we return the dereferenced value.
func (gu *gsUniformAttr) Value() interface{} {
if !gu.ispointer {
return gu.value
}
switch gu.Type {
case glhf.Vec2:
return *gu.value.(*mgl32.Vec2)
case glhf.Vec3:
return *gu.value.(*mgl32.Vec3)
case glhf.Vec4:
return *gu.value.(*mgl32.Vec4)
case glhf.Mat2:
return *gu.value.(*mgl32.Mat2)
case glhf.Mat23:
return *gu.value.(*mgl32.Mat2x3)
case glhf.Mat24:
return *gu.value.(*mgl32.Mat2x4)
case glhf.Mat3:
return *gu.value.(*mgl32.Mat3)
case glhf.Mat32:
return *gu.value.(*mgl32.Mat3x2)
case glhf.Mat34:
return *gu.value.(*mgl32.Mat3x4)
case glhf.Mat4:
return *gu.value.(*mgl32.Mat4)
case glhf.Mat42:
return *gu.value.(*mgl32.Mat4x2)
case glhf.Mat43:
return *gu.value.(*mgl32.Mat4x3)
case glhf.Int:
return *gu.value.(*int32)
case glhf.Float:
return *gu.value.(*float32)
default:
panic("invalid attrtype")
}
}
// Returns the type identifier for any (supported) attribute variable type
// and whether or not it is a pointer of that type.
func getAttrType(v interface{}) (glhf.AttrType, bool) {
switch v.(type) {
case int32:
return glhf.Int, false
case float32:
return glhf.Float, false
case mgl32.Vec2:
return glhf.Vec2, false
case mgl32.Vec3:
return glhf.Vec3, false
case mgl32.Vec4:
return glhf.Vec4, false
case mgl32.Mat2:
return glhf.Mat2, false
case mgl32.Mat2x3:
return glhf.Mat23, false
case mgl32.Mat2x4:
return glhf.Mat24, false
case mgl32.Mat3:
return glhf.Mat3, false
case mgl32.Mat3x2:
return glhf.Mat32, false
case mgl32.Mat3x4:
return glhf.Mat34, false
case mgl32.Mat4:
return glhf.Mat4, false
case mgl32.Mat4x2:
return glhf.Mat42, false
case mgl32.Mat4x3:
return glhf.Mat43, false
case *mgl32.Vec2:
return glhf.Vec2, true
case *mgl32.Vec3:
return glhf.Vec3, true
case *mgl32.Vec4:
return glhf.Vec4, true
case *mgl32.Mat2:
return glhf.Mat2, true
case *mgl32.Mat2x3:
return glhf.Mat23, true
case *mgl32.Mat2x4:
return glhf.Mat24, true
case *mgl32.Mat3:
return glhf.Mat3, true
case *mgl32.Mat3x2:
return glhf.Mat32, true
case *mgl32.Mat3x4:
return glhf.Mat34, true
case *mgl32.Mat4:
return glhf.Mat4, true
case *mgl32.Mat4x2:
return glhf.Mat42, true
case *mgl32.Mat4x3:
return glhf.Mat43, true
case *int32:
return glhf.Int, true
case *float32:
return glhf.Float, true
default:
panic("invalid AttrType")
}
}
in vec2 aPosition;
in vec4 aColor;
in vec2 aTexCoords;
in float aIntensity;
out vec4 vColor;
out vec2 vTexCoords;
out float vIntensity;
uniform mat3 uTransform;
uniform vec4 uBounds;
vec2 transPos = (uTransform * vec3(aPosition, 1.0)).xy;
vec2 normPos = (transPos - uBounds.xy) / uBounds.zw * 2 - vec2(1, 1);
gl_Position = vec4(normPos, 0.0, 1.0);
vColor = aColor;
vTexCoords = aTexCoords;
vIntensity = aIntensity;
}
`
var baseCanvasFragmentShader = `
#version 330 core
in vec4 vColor;
in vec2 vTexCoords;
in float vIntensity;
uniform vec4 uColorMask;
uniform vec4 uTexBounds;
uniform sampler2D uTexture;
if (vIntensity == 0) {
fragColor = uColorMask * vColor;
} else {
fragColor = vec4(0, 0, 0, 0);
fragColor += (1 - vIntensity) * vColor;
vec2 t = (vTexCoords - uTexBounds.xy) / uTexBounds.zw;
fragColor += vIntensity * vColor * texture(uTexture, t);
fragColor *= uColorMask;