77 lines
2.1 KiB
Go
77 lines
2.1 KiB
Go
package goglbackend
|
|
|
|
import (
|
|
"unsafe"
|
|
|
|
"github.com/tfriedel6/canvas/backend/backendbase"
|
|
"github.com/tfriedel6/canvas/backend/goglbackend/gl"
|
|
)
|
|
|
|
func (b *GoGLBackend) ClearClip() {
|
|
b.activate()
|
|
|
|
gl.StencilMask(0xFF)
|
|
gl.Clear(gl.STENCIL_BUFFER_BIT)
|
|
}
|
|
|
|
func (b *GoGLBackend) Clip(pts []backendbase.Vec) {
|
|
b.activate()
|
|
|
|
b.ptsBuf = b.ptsBuf[:0]
|
|
b.ptsBuf = append(b.ptsBuf,
|
|
0, 0,
|
|
0, float32(b.fh),
|
|
float32(b.fw), float32(b.fh),
|
|
float32(b.fw), 0)
|
|
for _, pt := range pts {
|
|
b.ptsBuf = append(b.ptsBuf, float32(pt[0]), float32(pt[1]))
|
|
}
|
|
|
|
mode := uint32(gl.TRIANGLES)
|
|
if len(pts) == 4 {
|
|
mode = gl.TRIANGLE_FAN
|
|
}
|
|
|
|
gl.BindBuffer(gl.ARRAY_BUFFER, b.buf)
|
|
gl.BufferData(gl.ARRAY_BUFFER, len(b.ptsBuf)*4, unsafe.Pointer(&b.ptsBuf[0]), gl.STREAM_DRAW)
|
|
gl.VertexAttribPointer(b.shd.Vertex, 2, gl.FLOAT, false, 0, nil)
|
|
gl.VertexAttribPointer(b.shd.TexCoord, 2, gl.FLOAT, false, 0, nil)
|
|
|
|
gl.UseProgram(b.shd.ID)
|
|
gl.Uniform4f(b.shd.Color, 1, 1, 1, 1)
|
|
gl.Uniform2f(b.shd.CanvasSize, float32(b.fw), float32(b.fh))
|
|
gl.UniformMatrix3fv(b.shd.Matrix, 1, false, &mat3identity[0])
|
|
gl.Uniform1f(b.shd.GlobalAlpha, 1)
|
|
gl.Uniform1i(b.shd.UseAlphaTex, 0)
|
|
gl.Uniform1i(b.shd.Func, shdFuncSolid)
|
|
gl.EnableVertexAttribArray(b.shd.Vertex)
|
|
gl.EnableVertexAttribArray(b.shd.TexCoord)
|
|
|
|
gl.ColorMask(false, false, false, false)
|
|
|
|
// set bit 2 in the stencil buffer in the given shape
|
|
gl.StencilMask(0x04)
|
|
gl.StencilFunc(gl.ALWAYS, 4, 0)
|
|
gl.StencilOp(gl.REPLACE, gl.REPLACE, gl.REPLACE)
|
|
gl.DrawArrays(mode, 4, int32(len(pts)))
|
|
|
|
// on entire screen, where neither bit 1 or 2 are set, invert bit 1
|
|
gl.StencilMask(0x02)
|
|
gl.StencilFunc(gl.EQUAL, 0, 0x06)
|
|
gl.StencilOp(gl.KEEP, gl.INVERT, gl.INVERT)
|
|
gl.DrawArrays(gl.TRIANGLE_FAN, 0, 4)
|
|
|
|
// on entire screen, clear bit 2
|
|
gl.StencilMask(0x04)
|
|
gl.StencilFunc(gl.ALWAYS, 0, 0)
|
|
gl.StencilOp(gl.ZERO, gl.ZERO, gl.ZERO)
|
|
gl.DrawArrays(gl.TRIANGLE_FAN, 0, 4)
|
|
|
|
gl.DisableVertexAttribArray(b.shd.Vertex)
|
|
gl.DisableVertexAttribArray(b.shd.TexCoord)
|
|
|
|
gl.ColorMask(true, true, true, true)
|
|
gl.StencilOp(gl.KEEP, gl.KEEP, gl.KEEP)
|
|
gl.StencilMask(0xFF)
|
|
gl.StencilFunc(gl.EQUAL, 0, 0xFF)
|
|
}
|