Help with creating a mesh

[lordulrich]

I am fairly experienced with python but new to blender, and am working with blender 2.5.
What i am trying to do is create a mesh object using python code. The function I came up with is:

def plotdem(dem):
    #function to take dem and plot in blender    
    verts=[]
    #nested for loops createing a list of all verts
    for y in range(0,len(dem[0])-1):
        for x in range(0,len(dem)-1):
            z=dem[x][y]
            verts.append((x,y,z))
    faces=[]
    
    leny=len(dem[0])
    lenx=len(dem)

    #nested for loops to create faces
    for y in range(1,leny-1):
        for x in range(1,lenx-1):            
            
                       
            pt00=(y-1)*leny+x-1
            pt01=(y-1)*leny+x
            pt10=y*leny+x-1
            pt11=y*leny+x           
            faces.append((pt00,pt01, pt11, pt10))        #add face to list of faces
               
    land = bpy.data.meshes.new("LandSurface")        
    ob = bpy.data.objects.new("LandSurface", land)
    ob.location=bpy.context.scene.cursor_location
    bpy.context.scene.objects.link(ob)                    
    land.from_pydata(verts,[],faces)                    #create object land
    land.update(calc_edges=True)                        #calculate mesh

dem is a 2 dimensional list object with the z values at a given xy location (ie z=dem[x][y]), this is created elsewhere in my code, and I know this part is working properly.

When I try to run the code blender crashes each time. If I run the code commenting out the last line it creates an object, but crashes if I try to enter edit mode, and as a weird (ie should not exist) “wall” along the y=0 line, and i am getting additional faces connecting to 0,0.

So what am I doing wrong? Thanks in advance

[lordulrich]

To make this easier for us, you could provide a processed Xn * Yn sample list of the list called ‘dem’

I am not exactly sure what you mean, but here is an example of the list dem

[[-2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0], [-2.0, -1.8706639375232588, -2.0, -1.9177709241145673, -1.5943104895667393, -2.0, -1.9914762217271043, -1.2562987052227887, -1.9059903338837776, -1.180425028395511, -1.681983666268006, -1.6910357919320622, -1.4582290999931606, -1.5320262633759145, -1.8618471451223175, -1.9347092932016854, -2.0, -1.9980760610736037, -1.9174313840342487, -2.0], [-2.0, -1.9359677951637817, -1.8982144892450823, -1.9910056292019884, -2.0, -1.5283347301198766, -1.2944984336850267, -1.2191534010855796, -0.975582746740528, -1.9319757959351032, -1.4323533376686077, -0.7867066076528723, -1.2680274791181776, -1.7170776721834018, -1.4769727340330379, -1.5351772931367462, -1.4760753588237856, -1.9246350655630302, -1.6256810451359505, -2.0], [-2.0, -1.9094156406807252, -2.0, -1.967488638771805, -1.5032529532211936, -0.9452760817668189, -0.8754850644992418, -0.762595227461413, -0.4423153893894067, -0.17897824075141872, -0.13810545896743132, -1.4381824620698194, -0.18985019135337217, -2.0, -0.8960798327948827, -0.8276709923960688, -1.7211686730193156, -1.4845940025086326, -1.8978274704679754, -2.0], [-2.0, -1.8650626114067308, -1.6421321579955652, -1.2966203609342877, -1.1786631957735958, -0.7413490716708933, -0.33896952652386286, -0.593803399522124, 0.13475051075465486, 0.47402237764436406, 0.6403152864695527, 0.5147100080807065, -0.24238653445442448, 0.12959671169172246, -0.1830385980653095, -0.7384859844264046, -0.8265553336613161, -1.7484117129343, -1.879038682894694, -2.0], [-2.0, -1.9683509646289916, -1.5228552448289656, -1.9394547371148319, -1.0486254281886007, 0.27858468339514003, 0.1606374993803691, 1.5919551796116975, 2.088054626278093, 1.1647216193145111, 2.2573467999454477, 1.2159995920536986, 1.4946781253289232, 0.8634952842081782, 0.5931664053141338, 0.11170836514677365, -0.8461153904984823, -0.9858153208132797, -0.9867117320025031, -2.0], [-2.0, -1.5415702604887684, -1.3880657651315373, -1.2026774955605726, -0.9629071424755964, -0.2292906636361971, 1.2225526704336378, 5.481835502147829, 1.9314036008790854, 3.6969857981021983, 3.6635752056955906, 2.9928376294188075, 2.885913961223082, 3.9700871060857024, 1.548178424252181, 1.0682489945570928, 0.1583602257754357, -1.3434997910378081, -1.3587001420693017, -2.0], [-2.0, -1.868329399385283, -1.1471473614934393, -0.9677065140820706, -0.6062153333250262, 0.18913875096475347, 1.434127646132253, 3.2692956965719024, 6.186764432692605, 2.6286829933483054, 3.6481523003437935, 4.587238518826684, 4.729279615339711, 3.7775361052414955, 3.3200129629757384, 1.7517101065794465, 0.5695091017251928, -0.3347097775622931, -0.2751335713484187, -2.0], [-2.0, -1.3197558835477872, -1.9816184893095545, -0.782919439159434, -0.24012747762536668, 1.705605928089364, 1.6556527410263786, 2.351782436749227, 5.06999591649486, 3.657324365500068, 5.583006928968977, 7.52999381802478, 3.990348512923793, 3.437318479198933, 3.3397920363408367, 3.097521488375092, 1.3747755354011482, 0.3498964151887495, -0.7789794699848069, -2.0], [-2.0, -1.8601480680219058, -1.0198593531957099, -0.927095797577735, -0.21303468363127326, 1.213554974529682, 1.2329088345818797, 2.334324570624877, 3.371643549702465, 11.293806282971376, 5.191194186907433, 5.302429923882369, 11.594189371062836, 5.463193964819342, 3.5733267495802346, 3.5341078823044367, 1.5473095121812082, 0.709054919138841, -1.1954703568238443, -2.0], [-2.0, -2.0, -1.067203247188803, -0.9935706162490854, -0.2707787918583821, 1.2251268795507304, 3.0220397949657203, 3.2678841572995716, 4.198049353100094, 4.2266257958401985, 5.510597793841073, 8.18439724285164, 5.003752259392373, 7.845958912362676, 3.8249530008186734, 3.169559984463609, 1.0363986028210679, 1.1811377826419727, 0.1462790767051326, -2.0], [-2.0, -1.941631640847955, -1.3196253621066607, -1.234837323562796, -0.4175717954651354, 0.49695888829092455, 1.2784011421975758, 3.4367855691838893, 3.772872715569071, 7.234052403510925, 7.8664617415509674, 4.970782923690901, 6.254551882896405, 8.019712234436149, 4.594357628311834, 3.0088576717981184, 1.0468123680221633, -1.783669444841597, 0.8112932827794084, -2.0], [-2.0, -2.0, -2.0, -1.8033349770027658, -0.34958680556240895, -0.3655909224309125, 1.7803381845548407, 4.113458755973308, 3.199358750387245, 5.521248893581313, 5.1877717445710525, 5.542052355393956, 11.382763890579286, 4.387543971654503, 4.628154368898873, 3.333026542964885, 1.5566516889185509, 0.9409078889386208, -1.6165642303526715, -2.0], [-2.0, -2.0, -2.0, -1.0963814516919748, -0.6737547227869943, -0.08740365290956573, 0.9744542905186766, 1.6363034507000858, 2.766844570668412, 3.7004192875771698, 11.433292492103067, 6.67308223266634, 1.8881995991183065, 4.110418944496971, 4.03459512550746, 2.762602856722033, 1.9878745563555213, 1.1756433185681594, 0.20325984586430138, -2.0], [-2.0, -2.0, -1.3344295878755659, -2.0, -1.9392376957644542, -0.09164513259794185, 0.597193411413879, 1.2635446483900536, 2.116302739269181, 4.188581517024461, 3.440691703362375, 3.577224714755262, 4.699139380524943, 3.7708435854197715, 2.8593220392574086, 2.552663066469908, 1.3984155602812678, 0.8048038304253238, 0.03634101205820557, -2.0], [-2.0, -1.7105989020295738, -1.6260454129699604, -1.6086982128950646, -1.050363113973172, -1.1310521513615028, 0.0565111007459015, 1.36962266794378, 1.9894628721652685, 1.9600344975945068, 2.053136009636224, 3.704841705290413, 3.44710560409843, 2.84359891023833, 2.9801361875572168, 1.6767944542926851, 1.1750553557322163, 0.4943172779602172, 0.16248483599556107, -2.0], [-2.0, -1.9373832559802726, -1.7035807432839416, -1.5081848863055987, -1.228371221763549, -1.053092716254403, -0.4545480267597594, -0.2958395204140891, -0.3787400349624512, 0.5233767761203251, 1.2663556689435125, 0.5593929100304266, 1.9419516338884886, 1.8894776448217565, 1.3063287366727756, 1.276734968866831, -1.1004991821156493, 0.10530797679108117, -0.26599620911814703, -2.0], [-2.0, -2.0, -1.725485418632833, -1.6203830726812811, -1.3486080866854055, -1.3061646521482222, -0.9926590016370451, -0.4618775483103885, 0.21855634071004715, 0.4098098086557155, 0.22207743360894258, 0.9711767465211174, -1.9002605560172232, 1.1247259121637112, 0.9571555907300336, 0.45916916603149016, 0.08868692460424316, -0.594915243501883, -0.35475934830261857, -2.0], [-2.0, -1.9327249948845446, -1.7283483363495278, -2.0, -1.8218735249729123, -1.452006931092301, -1.0039775081228002, -1.2590119423111439, -0.3811491876536563, -0.10190145868980645, 0.07032128482451519, -1.1449711777550533, -0.784012825959388, 0.1391470280598081, 0.22738294685617894, -0.03291376986715735, -0.12820960994290567, -0.4870294666790773, -0.9484130058462262, -2.0], [-2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0]]

The above list is much shorter than in practice to meet post size limit requirements.

[zeffii]

It looks like your problem is that you don’t in fact have functional x,y coordinates for every z.

import bpy

# Constants, for testing.
ZOOM_RES = 1e4
XY_SPREAD = 1

# assumes a square matrix of Z values
def CreateMeshUsingMatrix(VertIndices, Verts):

    Faces = []
    dims = len(VertIndices) # this assumes x,y ratio is 1:1

    # going to use current row and next row all the way down
    for row in range(dims-1):
        #now take row and row+1
        for col in range(dims-1):
            #we generate faces clockwise from 4 Verts
            val1 = VertIndices[row][col]
            val2 = VertIndices[row][col+1]
            val3 = VertIndices[row+1][col+1]
            val4 = VertIndices[row+1][col]
            face = [val1, val2, val3, val4]
            Faces.append(face)
        

    ## TAKEN FROM USER    ValterVB 
    # create new mesh structure
    mesh = bpy.data.meshes.new("Relief")
    mesh.from_pydata(Verts, [], Faces)
    mesh.update()
    # create an object from this mesh
    new_object = bpy.data.objects.new("Ascii Data", mesh)
    new_object.data = mesh
    # adding object called "Ascii Data" to the scene
    scene = bpy.context.scene
    scene.objects.link(new_object)
    # deals with selecting
    scene.objects.active = new_object
    new_object.select = True



def start_mesh_creation(heightMatrix):
    VertIndices = []
    
    # this supposes that X, Y separation are going to be the same.
    xy_val = []
    for i in range(len(heightMatrix)): # NOTE: or len(heightMatrix[0]) whichever is longer.
        xy_val.append(i*XY_SPREAD)

    # Generates the (x,y,height) matrix, no need for Vector(...) 
    yVal = 0
    vertNum = 0
    rawVertCollection = []
    for height_x in heightMatrix:
        xVal = 0
        vertRow = []
        for item in height_x:
            t_vertice = (xy_val[xVal], -xy_val[yVal], heightMatrix[yVal][xVal])
            rawVertCollection.append(t_vertice)
            
            vertRow.append(vertNum)
            xVal+=1
            vertNum+=1
        yVal+=1
        VertIndices.append(vertRow)

    # done here, lets make a mesh! 
    CreateMeshUsingMatrix(VertIndices, rawVertCollection)


start_mesh_creation(dem)

you might tweak this if you have a input data that isn’t n*n

you might have to flip normals afterwards, if you want to texture this.

[zeffii]