luanti-extended-engine-features/leef-math-cd2025
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

(breaking) simplify mat4.project and unproject

Browse Source 
the separate view and projection just weren't really useful, might as
well pass in your own full transform instead.

this also fixes the z range, which should not have been manipulated.
this simplifies usage to check something as on screen to just 1 > z > 0

might break the test, but tested working locally
This commit is contained in:
Colby Klein 2022-04-30 14:10:51 -07:00
parent e34ab20d82
commit 7d22d13bca
2 changed files with 32 additions and 51 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
modules/mat4.lua
View File

@ -652,54 +652,37 @@ function mat4.transpose(out, a)
return out
end
-- https://github.com/g-truc/glm/blob/master/glm/gtc/matrix_transform.inl#L518
--- Project a matrix from world space to screen space.
--- Project a point into screen space
-- @tparam vec3 obj Object position in world space
-- @tparam mat4 view View matrix
-- @tparam mat4 projection Projection matrix
-- @tparam mat4 mvp Projection matrix
-- @tparam table viewport XYWH of viewport
-- @treturn vec3 win
function mat4.project(obj, view, projection, viewport)
local position = { obj.x, obj.y, obj.z, 1 }
mat4.mul_vec4(position, view, position)
mat4.mul_vec4(position, projection, position)
position[1] = position[1] / position[4] * 0.5 + 0.5
position[2] = position[2] / position[4] * 0.5 + 0.5
position[3] = position[3] / position[4] * 0.5 + 0.5
position[1] = position[1] * viewport[3] + viewport[1]
position[2] = position[2] * viewport[4] + viewport[2]
return vec3(position[1], position[2], position[3])
function mat4.project(obj, mvp, viewport)
local point = mat4.mul_vec3_perspective(vec3(), mvp, obj)
point.x = point.x * 0.5 + 0.5
point.y = point.y * 0.5 + 0.5
point.x = point.x * viewport[3] + viewport[1]
point.y = point.y * viewport[4] + viewport[2]
return point
end
-- https://github.com/g-truc/glm/blob/master/glm/gtc/matrix_transform.inl#L544
--- Unproject a matrix from screen space to world space.
--- Unproject a point from screen space to world space.
-- @tparam vec3 win Object position in screen space
-- @tparam mat4 view View matrix
-- @tparam mat4 projection Projection matrix
-- @tparam mat4 mvp Projection matrix
-- @tparam table viewport XYWH of viewport
-- @treturn vec3 obj
function mat4.unproject(win, view, projection, viewport)
local position = { win.x, win.y, win.z, 1 }
function mat4.unproject(win, mvp, viewport)
local point = vec3.clone(win)
position[1] = (position[1] - viewport[1]) / viewport[3]
position[2] = (position[2] - viewport[2]) / viewport[4]
-- 0..n -> 0..1
point.x = (point.x - viewport[1]) / viewport[3]
point.y = (point.y - viewport[2]) / viewport[4]
position[1] = position[1] * 2 - 1
position[2] = position[2] * 2 - 1
position[3] = position[3] * 2 - 1
-- 0..1 -> -1..1
point.x = point.x * 2 - 1
point.y = point.y * 2 - 1
tmp:mul(projection, view):invert(tmp)
mat4.mul_vec4(position, tmp, position)
position[1] = position[1] / position[4]
position[2] = position[2] / position[4]
position[3] = position[3] / position[4]
return vec3(position[1], position[2], position[3])
return mat4.mul_vec3_perspective(point, tmp:invert(mvp), point)
end
--- Return a boolean showing if a table is or is not a mat4.

26
spec/mat4_spec.lua
View File

@ -301,27 +301,25 @@ describe("mat4:", function()
assert.is.equal(p.z, 5)
end)
it("projects a matrix into screen space", function()
local v = vec3(0, 0, 10)
local a = mat4()
local b = mat4.from_perspective(45, 1, 0.1, 1000)
it("projects a point into screen space", function()
local p = vec3(0, 0, 10)
local proj = mat4.from_perspective(45, 1, 0.1, 1000)
local vp = { 0, 0, 400, 400 }
local c = mat4.project(v, a, b, vp)
local c = mat4.project(p, proj, vp)
assert.is.equal(200, c.x)
assert.is.equal(200, c.y)
assert.is_true(utils.tolerance(1.0101-c.z, 0.001))
end)
it("unprojects a matrix into world space", function()
local v = vec3(0, 0, 10)
local a = mat4()
local b = mat4.from_perspective(45, 1, 0.1, 1000)
it("unprojects a point into world space", function()
local p = vec3(0, 0, 10)
local proj = mat4.from_perspective(45, 1, 0.1, 1000)
local vp = { 0, 0, 400, 400 }
local c = mat4.project(v, a, b, vp)
local d = mat4.unproject(c, a, b, vp)
assert.is_true(utils.tolerance(v.x-d.x, 0.001))
assert.is_true(utils.tolerance(v.y-d.y, 0.001))
assert.is_true(utils.tolerance(v.z-d.z, 0.001))
local c = mat4.project(p, proj, vp)
local d = mat4.unproject(c, proj, vp)
assert.is_true(utils.tolerance(p.x-d.x, 0.001))
assert.is_true(utils.tolerance(p.y-d.y, 0.001))
assert.is_true(utils.tolerance(p.z-d.z, 0.001))
end)
it("transforms a matrix to look at a point", function()