From 1870c49c4a51006c87aef316c52ac9e5f11c4334 Mon Sep 17 00:00:00 2001
From: soypat <graded.sp@gmail.com>
Date: Mon, 25 Nov 2024 01:56:10 -0300
Subject: [PATCH] work on adding poly gpu processing

---
 examples/ui-text/uitext.go |  3 ++-
 gsdf.go                    | 18 +++++++++++++++++
 gsdf2d.go                  | 41 ++++++++++++++++++++++++++++++++++++++
 gsdfaux/ui.go              |  6 ++++--
 4 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/examples/ui-text/uitext.go b/examples/ui-text/uitext.go
index 211354c..819aae1 100644
--- a/examples/ui-text/uitext.go
+++ b/examples/ui-text/uitext.go
@@ -55,6 +55,7 @@ func main() {
 		Height: 600,
 	})
 	if err != nil {
-		log.Fatal("UI:", err)
+		fmt.Println(err)
+		return
 	}
 }
diff --git a/gsdf.go b/gsdf.go
index 78a68b6..99508d7 100644
--- a/gsdf.go
+++ b/gsdf.go
@@ -4,6 +4,7 @@ import (
 	_ "embed"
 	"errors"
 	"fmt"
+	"unsafe"
 
 	"github.com/chewxy/math32"
 	"github.com/soypat/glgl/math/ms2"
@@ -35,6 +36,23 @@ type Builder struct {
 	// flags is a bitfield controlling behaviour of Builder.
 	flags     Flags
 	accumErrs []error
+	// limVecGPU
+	limVecGPU int
+}
+
+func (bld *Builder) useGPU(n int) bool {
+	return bld.limVecGPU != 0 && n > bld.limVecGPU || n > 1024
+}
+
+func makeHashName[T any](dst []byte, name string, vec []T) []byte {
+	var z T
+	data := unsafe.Pointer(&vec[0])
+	bdata := unsafe.Slice((*byte)(data), len(vec)*int(unsafe.Sizeof(z)))
+	_ = bdata
+	// for _, b := range bdata {
+
+	// }
+	return fmt.Appendf(dst, "%s%x", name, uintptr(data))
 }
 
 func (bld *Builder) Flags() Flags {
diff --git a/gsdf2d.go b/gsdf2d.go
index 8b1e2e9..a5c358c 100644
--- a/gsdf2d.go
+++ b/gsdf2d.go
@@ -555,6 +555,10 @@ func (bld *Builder) NewPolygon(vertices []ms2.Vec) glbuild.Shader2D {
 		}
 		prevIdx = i
 	}
+	println("poly")
+	// if bld.useGPU(len(vertices)) {
+	// 	return &polyGPU{poly2D: poly2D{vert: vertices}, bufname: makeHashName(nil, "ssboPoly", vertices)}
+	// }
 	return &poly2D{vert: vertices}
 }
 
@@ -609,6 +613,43 @@ func (u *poly2D) AppendShaderObjects(objects []glbuild.ShaderObject) []glbuild.S
 	return objects // TODO: implement shader buffer storage here!
 }
 
+type polyGPU struct {
+	poly2D
+	bufname []byte
+}
+
+func (c *polyGPU) AppendShaderBody(b []byte) []byte {
+	b = glbuild.AppendDefineDecl(b, "ver", string(c.bufname))
+	b = append(b, `const int num = v.length();
+float d = dot(p-v[0],p-v[0]);
+float s = 1.0;
+for( int i=0, j=num-1; i<num; j=i, i++ )
+{
+	// distance
+	vec2 e = v[j] - v[i];
+	vec2 w = p - v[i];
+	vec2 b = w - e*clamp( dot(w,e)/dot(e,e), 0.0, 1.0 );
+	d = min( d, dot(b,b) );
+	// winding number from http://geomalgorithms.com/a03-_inclusion.html
+	bvec3 cond = bvec3( p.y>=v[i].y, 
+						p.y <v[j].y, 
+						e.x*w.y>e.y*w.x );
+	if( all(cond) || all(not(cond)) ) s=-s;  
+}
+return s*sqrt(d);
+`...)
+	b = glbuild.AppendUndefineDecl(b, "ver")
+	return b
+}
+
+func (u *polyGPU) AppendShaderObjects(objects []glbuild.ShaderObject) []glbuild.ShaderObject {
+	ssbo, err := glbuild.MakeShaderBufferReadOnly(u.bufname, u.vert)
+	if err != nil {
+		panic(err)
+	}
+	return append(objects, ssbo)
+}
+
 // Extrude converts a 2D SDF into a 3D extrusion. Extrudes in both positive and negative Z direction, half of h both ways.
 func (bld *Builder) Extrude(s glbuild.Shader2D, h float32) glbuild.Shader3D {
 	if s == nil {
diff --git a/gsdfaux/ui.go b/gsdfaux/ui.go
index 6513c9e..1d3adb4 100644
--- a/gsdfaux/ui.go
+++ b/gsdfaux/ui.go
@@ -4,6 +4,7 @@ package gsdfaux
 
 import (
 	"bytes"
+	"fmt"
 	"log"
 	"math"
 	"time"
@@ -35,6 +36,7 @@ func ui(s glbuild.Shader3D, cfg UIConfig) error {
 	}
 	// Print OpenGL version
 	// // Compile shaders and link program
+	fragSrc := makeFragSource(root, sdfDecl.String())
 	prog, err := glgl.CompileProgram(glgl.ShaderSource{
 		Vertex: `#version 460
 in vec2 aPos;
@@ -44,10 +46,10 @@ void main() {
     gl_Position = vec4(aPos, 0.0, 1.0);
 }
 ` + "\x00",
-		Fragment: makeFragSource(root, sdfDecl.String()),
+		Fragment: fragSrc,
 	})
 	if err != nil {
-		log.Fatal(err)
+		return fmt.Errorf("%s\n\n%w", fragSrc, err)
 	}
 	prog.Bind()
 	// Define a quad covering the screen