TriangleZbuffering

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Nov 6th, 2021

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local function drawFlatTriangle(ZBUFFER,px1,px2,y,color,v1,v2,v3,inV1,inV2,inV3)
local xStart = math.ceil(px1-0.5)
local xEnd = math.ceil(px2-0.5)
local sxStart = intY(inV1,inV2,y)
local sxEnd = intY(inV1,inV3,y)
local p1 = vector.new(sxStart,y)
local p2 = vector.new(sxEnd,y)
local t1 = getT(inV1,inV2,p1)
local t2 = getT(inV1,inV3,p2)
local z1 = lerp(inV1.w,inV2.w,t1)
local z2 = lerp(inV1.w,inV3.w,t2)
for x = xStart, xEnd do
if y > 0 and x > 0 then
local t3 = (x - sxStart) / (sxEnd - sxStart)
local wCur = math.floor(lerp(z1,z2,t3))
if not ZBUFFER[x][y] then ZBUFFER[x][y] = {w=math.huge} end
if wCur <= ZBUFFER[x][y].w or ZBUFFER[x][y].w == math.huge then
ZBUFFER[x][y] = {
color=color,
w=wCur
}
end
end
end
end
local function drawFlatTopTriangle(ZBUFFER,vec1,vec2,vec3,color,insVec1,insVec2,insVec3)
local m1 = (vec3.x - vec1.x) / (vec3.y - vec1.y)
local m2 = (vec3.x - vec2.x) / (vec3.y - vec2.y)
local yStart = math.ceil(vec1.y - 0.5)
local yEnd = math.ceil(vec3.y - 0.5)-1
for y = yStart, yEnd do
local px1 = m1 * (y + 0.5 - vec1.y) + vec1.x
local px2 = m2 * (y + 0.5 - vec2.y) + vec2.x
drawFlatTriangle(ZBUFFER,px1,px2,y,color,vec1,vec2,vec3,insVec1,insVec2,insVec3)
end
end
local function drawFlatBottomTriangle( ZBUFFER,vec1,vec2,vec3,color,insVec1,insVec2,insVec3)
local m1 = (vec2.x - vec1.x) / (vec2.y - vec1.y)
local m2 = (vec3.x - vec1.x) / (vec3.y - vec1.y)
local yStart = math.ceil(vec1.y-0.5)
local yEnd = math.ceil(vec3.y-0.5)-1
for y = yStart, yEnd do
local px1 = m1 * (y + 0.5 - vec1.y) + vec1.x
local px2 = m2 * (y + 0.5 - vec1.y) + vec1.x
drawFlatTriangle(ZBUFFER,px1,px2,y,color,vec1,vec2,vec3,insVec1,insVec2,insVec3)
end
end
local function proccesSolidTriangle(ZBUFFER,vec1,vec2,vec3,color)
local pv1 = vec1
local pv2 = vec2
local pv3 = vec3
if pv2.y < pv1.y then pv1,pv2 = pv2,pv1 end
if pv3.y < pv2.y then pv2,pv3 = pv3,pv2 end
if pv2.y < pv1.y then pv1,pv2 = pv2,pv1 end
if pv1.y == pv2.y then
if pv2.x < pv1.x then pv1,pv2 = pv2,pv1 end
drawFlatTopTriangle(ZBUFFER,pv1,pv2,pv3,color,vec1,vec2,vec3)
elseif pv2.y == pv3.y then
if pv3.x < pv2.x then pv3,pv2 = pv2,pv3 end
drawFlatBottomTriangle(ZBUFFER,pv1,pv2,pv3,color,vec1,vec2,vec3)
else
local alphaSplit = (pv2.y-pv1.y)/(pv3.y-pv1.y)
local vi ={
x = pv1.x + ((pv3.x - pv1.x) * alphaSplit),
y = pv1.y + ((pv3.y - pv1.y) * alphaSplit), }
if pv2.x < vi.x then
drawFlatBottomTriangle(ZBUFFER,pv1,pv2,vi,color,vec1,vec2,vec3)
drawFlatTopTriangle(ZBUFFER,pv2,vi,pv3,color,vec1,vec2,vec3)
else
drawFlatBottomTriangle(ZBUFFER,pv1,vi,pv2,color,vec1,vec2,vec3)
drawFlatTopTriangle(ZBUFFER,vi,pv2,pv3,color,vec1,vec2,vec3)
end
end
end

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