all: initial import

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/app/internal/gl/util.go

@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package gl
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+	"strings"
+	"unsafe"
+)
+
+func CreateProgram(ctx *Functions, vsSrc, fsSrc string, attribs []string) (Program, error) {
+	vs, err := createShader(ctx, VERTEX_SHADER, vsSrc)
+	if err != nil {
+		return 0, err
+	}
+	defer ctx.DeleteShader(vs)
+	fs, err := createShader(ctx, FRAGMENT_SHADER, fsSrc)
+	if err != nil {
+		return 0, err
+	}
+	defer ctx.DeleteShader(fs)
+	prog := ctx.CreateProgram()
+	if prog == 0 {
+		return 0, errors.New("glCreateProgram failed")
+	}
+	ctx.AttachShader(prog, vs)
+	ctx.AttachShader(prog, fs)
+	for i, a := range attribs {
+		ctx.BindAttribLocation(prog, Attrib(i), a)
+	}
+	ctx.LinkProgram(prog)
+	if ctx.GetProgrami(prog, LINK_STATUS) == 0 {
+		log := ctx.GetProgramInfoLog(prog)
+		ctx.DeleteProgram(prog)
+		return 0, fmt.Errorf("program link failed: %s", strings.TrimSpace(log))
+	}
+	return prog, nil
+}
+
+func GetUniformLocation(ctx *Functions, prog Program, name string) Uniform {
+	loc := ctx.GetUniformLocation(prog, name)
+	if loc == -1 {
+		panic(fmt.Errorf("uniform %s not found", name))
+	}
+	return loc
+}
+
+func createShader(ctx *Functions, typ Enum, src string) (Shader, error) {
+	sh := ctx.CreateShader(typ)
+	if sh == 0 {
+		return 0, errors.New("glCreateShader failed")
+	}
+	ctx.ShaderSource(sh, src)
+	ctx.CompileShader(sh)
+	if ctx.GetShaderi(sh, COMPILE_STATUS) == 0 {
+		log := ctx.GetShaderInfoLog(sh)
+		ctx.DeleteShader(sh)
+		return 0, fmt.Errorf("shader compilation failed: %s", strings.TrimSpace(log))
+	}
+	return sh, nil
+}
+
+// BytesView returns a byte slice view of a slice.
+func BytesView(s interface{}) []byte {
+	v := reflect.ValueOf(s)
+	first := v.Index(0)
+	sz := int(first.Type().Size())
+	return *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
+		Data: uintptr(unsafe.Pointer((*reflect.SliceHeader)(unsafe.Pointer(first.UnsafeAddr())))),
+		Len:  v.Len() * sz,
+		Cap:  v.Cap() * sz,
+	}))
+}
+
+func ParseGLVersion(glVer string) ([2]int, error) {
+	var ver [2]int
+	if _, err := fmt.Sscanf(glVer, "OpenGL ES %d.%d", &ver[0], &ver[1]); err != nil {
+		if _, err := fmt.Sscanf(glVer, "%d.%d", &ver[0], &ver[1]); err != nil {
+			return [2]int{}, fmt.Errorf("failed to parse OpenGL ES version (%s): %v", glVer, err)
+		}
+	}
+	return ver, nil
+}