func (e *Engine) Draw(c size.Event) {
gl.Enable(gl.DEPTH_TEST)
gl.DepthFunc(gl.LESS)
gl.ClearColor(0.2, 0.2, 0.2, 1)
gl.Clear(gl.COLOR_BUFFER_BIT)
gl.Clear(gl.DEPTH_BUFFER_BIT)
gl.UseProgram(e.shader.program)
m := mgl32.Perspective(0.785, float32(c.WidthPt/c.HeightPt), 0.1, 10.0)
gl.UniformMatrix4fv(e.shader.projection, m[:])
eye := mgl32.Vec3{0, 0, 8}
center := mgl32.Vec3{0, 0, 0}
up := mgl32.Vec3{0, 1, 0}
m = mgl32.LookAtV(eye, center, up)
gl.UniformMatrix4fv(e.shader.view, m[:])
m = mgl32.HomogRotate3D(float32(e.touchLoc.X/c.WidthPt-0.5)*3.14*2, mgl32.Vec3{0, 1, 0})
gl.UniformMatrix4fv(e.shader.modelx, m[:])
m = mgl32.HomogRotate3D(float32(e.touchLoc.Y/c.HeightPt-0.5)*3.14, mgl32.Vec3{1, 0, 0})
gl.UniformMatrix4fv(e.shader.modely, m[:])
coordsPerVertex := 3
for _, obj := range e.shape.Objs {
gl.BindBuffer(gl.ARRAY_BUFFER, obj.coord)
gl.EnableVertexAttribArray(e.shader.vertCoord)
gl.VertexAttribPointer(e.shader.vertCoord, coordsPerVertex, gl.FLOAT, false, 12, 0)
if obj.useuv == true {
gl.Uniform1i(e.shader.useuv, 1)
texCoordsPerVertex := 2
gl.BindBuffer(gl.ARRAY_BUFFER, obj.uvcoord)
gl.EnableVertexAttribArray(e.shader.vertTexCoord)
gl.VertexAttribPointer(e.shader.vertTexCoord, texCoordsPerVertex, gl.FLOAT, false, 8, 0)
gl.BindTexture(gl.TEXTURE_2D, obj.tex)
} else {
gl.Uniform1i(e.shader.useuv, 0)
gl.Uniform4f(e.shader.color, obj.color[0], obj.color[1], obj.color[2], obj.color[3])
}
gl.DrawArrays(gl.TRIANGLES, 0, obj.vcount)
if obj.useuv {
gl.DisableVertexAttribArray(e.shader.vertTexCoord)
}
gl.DisableVertexAttribArray(e.shader.vertCoord)
}
debug.DrawFPS(c)
}
func (w *windowImpl) Draw(src2dst f64.Aff3, src screen.Texture, sr image.Rectangle, op draw.Op, opts *screen.DrawOptions) {
t := src.(*textureImpl)
a := w.vertexAff3(sr)
gl.UseProgram(w.s.texture.program)
writeAff3(w.s.texture.mvp, mul(a, src2dst))
// OpenGL's fragment shaders' UV coordinates run from (0,0)-(1,1),
// unlike vertex shaders' XY coordinates running from (-1,+1)-(+1,-1).
//
// We are drawing a rectangle PQRS, defined by two of its
// corners, onto the entire texture. The two quads may actually
// be equal, but in the general case, PQRS can be smaller.
//
// (0,0) +---------------+ (1,0)
// | P +-----+ Q |
// | | | |
// | S +-----+ R |
// (0,1) +---------------+ (1,1)
//
// The PQRS quad is always axis-aligned. First of all, convert
// from pixel space to texture space.
tw := float64(t.size.X)
th := float64(t.size.Y)
px := float64(sr.Min.X-0) / tw
py := float64(sr.Min.Y-0) / th
qx := float64(sr.Max.X-0) / tw
sy := float64(sr.Max.Y-0) / th
// Due to axis alignment, qy = py and sx = px.
//
// The simultaneous equations are:
// 0 + 0 + a02 = px
// 0 + 0 + a12 = py
// a00 + 0 + a02 = qx
// a10 + 0 + a12 = qy = py
// 0 + a01 + a02 = sx = px
// 0 + a11 + a12 = sy
writeAff3(w.s.texture.uvp, f64.Aff3{
qx - px, 0, px,
0, sy - py, py,
})
gl.ActiveTexture(gl.TEXTURE0)
gl.BindTexture(gl.TEXTURE_2D, t.id)
gl.Uniform1i(w.s.texture.sample, 0)
gl.BindBuffer(gl.ARRAY_BUFFER, w.s.texture.quadXY)
gl.EnableVertexAttribArray(w.s.texture.pos)
gl.VertexAttribPointer(w.s.texture.pos, 2, gl.FLOAT, false, 0, 0)
gl.BindBuffer(gl.ARRAY_BUFFER, w.s.texture.quadUV)
gl.EnableVertexAttribArray(w.s.texture.inUV)
gl.VertexAttribPointer(w.s.texture.inUV, 2, gl.FLOAT, false, 0, 0)
gl.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
gl.DisableVertexAttribArray(w.s.texture.pos)
gl.DisableVertexAttribArray(w.s.texture.inUV)
}
func onPaint(sz size.Event) {
gl.ClearColor(rgb(156), rgb(39), rgb(176), 1)
gl.Clear(gl.COLOR_BUFFER_BIT)
var rotationMatrix = []float32{
f32.Cos(-alpha), -f32.Sin(-alpha), 0.0,
f32.Sin(-alpha), f32.Cos(-alpha), 0.0,
0.0, 0.0, 1.0,
}
gl.UseProgram(program)
// setting color
gl.Uniform4f(color, rgb(255), rgb(255), rgb(255), 1)
gl.UniformMatrix3fv(matrixId, rotationMatrix)
gl.Uniform1f(resolutionId, resIndex)
gl.BindBuffer(gl.ARRAY_BUFFER, swasBuffer)
gl.EnableVertexAttribArray(position)
gl.VertexAttribPointer(position, 3, gl.FLOAT, false, 0, 0)
gl.DrawArrays(gl.LINES, 0, 16)
gl.DisableVertexAttribArray(position)
gl.UseProgram(texProgram)
// setting color
gl.Uniform4f(color2, rgb(130), rgb(50), rgb(80), 1)
gl.Uniform1f(resolutionId2, resIndex)
gl.UniformMatrix3fv(matrixId2, rotationMatrix)
gl.BindBuffer(gl.ARRAY_BUFFER, quadBuffer)
gl.EnableVertexAttribArray(position2)
gl.VertexAttribPointer(position2, 3, gl.FLOAT, false, 0, 0)
gl.BindBuffer(gl.ARRAY_BUFFER, quadTexBuffer)
gl.EnableVertexAttribArray(textureCoords)
gl.VertexAttribPointer(textureCoords, 2, gl.FLOAT, false, 0, 0)
gl.Uniform1i(gl.GetUniformLocation(texProgram, "myTexture"), 0)
gl.ActiveTexture(gl.TEXTURE0)
gl.BindTexture(gl.TEXTURE_2D, textureId)
gl.DrawArrays(gl.TRIANGLES, 0, 6)
gl.DisableVertexAttribArray(position2)
gl.DisableVertexAttribArray(textureCoords)
if spin == true {
alpha += 0.1
}
if alpha >= 360 {
alpha = 0.0
}
}
// Draw draws the srcBounds part of the image onto a parallelogram, defined by
// three of its corners, in the current GL framebuffer.
func (img *Image) Draw(topLeft, topRight, bottomLeft geom.Point, srcBounds image.Rectangle) {
// TODO(crawshaw): Adjust viewport for the top bar on android?
gl.UseProgram(glimage.program)
{
// We are drawing a parallelogram PQRS, defined by three of its
// corners, onto the entire GL framebuffer ABCD. The two quads may
// actually be equal, but in the general case, PQRS can be smaller,
// and PQRS is not necessarily axis-aligned.
//
// A +---------------+ B
// | P +-----+ Q |
// | | | |
// | S +-----+ R |
// D +---------------+ C
//
// There are two co-ordinate spaces: geom space and framebuffer space.
// In geom space, the ABCD rectangle is:
//
// (0, 0) (geom.Width, 0)
// (0, geom.Height) (geom.Width, geom.Height)
//
// and the PQRS quad is:
//
// (topLeft.X, topLeft.Y) (topRight.X, topRight.Y)
// (bottomLeft.X, bottomLeft.Y) (implicit, implicit)
//
// In framebuffer space, the ABCD rectangle is:
//
// (-1, +1) (+1, +1)
// (-1, -1) (+1, -1)
//
// First of all, convert from geom space to framebuffer space. For
// later convenience, we divide everything by 2 here: px2 is half of
// the P.X co-ordinate (in framebuffer space).
px2 := -0.5 + float32(topLeft.X/geom.Width)
py2 := +0.5 - float32(topLeft.Y/geom.Height)
qx2 := -0.5 + float32(topRight.X/geom.Width)
qy2 := +0.5 - float32(topRight.Y/geom.Height)
sx2 := -0.5 + float32(bottomLeft.X/geom.Width)
sy2 := +0.5 - float32(bottomLeft.Y/geom.Height)
// Next, solve for the affine transformation matrix
// [ a00 a01 a02 ]
// a = [ a10 a11 a12 ]
// [ 0 0 1 ]
// that maps A to P:
// a × [ -1 +1 1 ]' = [ 2*px2 2*py2 1 ]'
// and likewise maps B to Q and D to S. Solving those three constraints
// implies that C maps to R, since affine transformations keep parallel
// lines parallel. This gives 6 equations in 6 unknowns:
// -a00 + a01 + a02 = 2*px2
// -a10 + a11 + a12 = 2*py2
// +a00 + a01 + a02 = 2*qx2
// +a10 + a11 + a12 = 2*qy2
// -a00 - a01 + a02 = 2*sx2
// -a10 - a11 + a12 = 2*sy2
// which gives:
// a00 = (2*qx2 - 2*px2) / 2 = qx2 - px2
// and similarly for the other elements of a.
glimage.mvp.WriteAffine(&f32.Affine{{
qx2 - px2,
px2 - sx2,
qx2 + sx2,
}, {
qy2 - py2,
py2 - sy2,
qy2 + sy2,
}})
}
{
// Mapping texture co-ordinates is similar, except that in texture
// space, the ABCD rectangle is:
//
// (0,0) (1,0)
// (0,1) (1,1)
//
// and the PQRS quad is always axis-aligned. First of all, convert
// from pixel space to texture space.
w := float32(img.texWidth)
h := float32(img.texHeight)
px := float32(srcBounds.Min.X-img.Rect.Min.X) / w
py := float32(srcBounds.Min.Y-img.Rect.Min.Y) / h
qx := float32(srcBounds.Max.X-img.Rect.Min.X) / w
sy := float32(srcBounds.Max.Y-img.Rect.Min.Y) / h
// Due to axis alignment, qy = py and sx = px.
//
// The simultaneous equations are:
// 0 + 0 + a02 = px
// 0 + 0 + a12 = py
// a00 + 0 + a02 = qx
// a10 + 0 + a12 = qy = py
// 0 + a01 + a02 = sx = px
// 0 + a11 + a12 = sy
glimage.uvp.WriteAffine(&f32.Affine{{
qx - px,
0,
px,
}, {
0,
sy - py,
py,
}})
}
gl.ActiveTexture(gl.TEXTURE0)
gl.BindTexture(gl.TEXTURE_2D, img.Texture)
gl.Uniform1i(glimage.textureSample, 0)
gl.BindBuffer(gl.ARRAY_BUFFER, glimage.quadXY)
gl.EnableVertexAttribArray(glimage.pos)
gl.VertexAttribPointer(glimage.pos, 2, gl.FLOAT, false, 0, 0)
gl.BindBuffer(gl.ARRAY_BUFFER, glimage.quadUV)
gl.EnableVertexAttribArray(glimage.inUV)
gl.VertexAttribPointer(glimage.inUV, 2, gl.FLOAT, false, 0, 0)
gl.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
gl.DisableVertexAttribArray(glimage.pos)
gl.DisableVertexAttribArray(glimage.inUV)
}