opengl es - mat4.lookat webgl clips view -


mat4.lookat() below giving me unexpected results. please see images associated 3 test examples. first example "correct", , others seem clipped, cannot figure why. perspectives , distances camera seem correct on all, except first, not getting whole view want. can suggest need adjust this?

function draw() {       gl.clearcolor(bgcolor[0],bgcolor[1],bgcolor[2],1);     gl.clear(gl.color_buffer_bit | gl.depth_buffer_bit);      if (document.getelementbyid("persproj").checked) {     mat4.perspective(projection, math.pi/4, 1, 4, 8);     }     else {     mat4.ortho(projection,-2.5, 2.5, -2.5, 2.5, 4, 8);     }     gl.uniformmatrix4fv(uprojection, false, projection );      mat4.lookat(modelview, [0,0,6], [0,0,0], [0,1,0]); // key line     mat4.rotatex(modelview, modelview, rotatex);     mat4.rotatey(modelview, modelview, rotatey);     gl.uniformmatrix4fv(umodelview, false, modelview );      mat3.normalfrommat4(normalmatrix, modelview);     gl.uniformmatrix3fv(unormalmatrix, false, normalmatrix);      gl.uniform1i( ulit, 0 );  // lines representing coordinate axes not lit.      gl.linewidth(4);     drawprimitive( gl.lines, [1,0,0,1], [ -2,0,0, 2,0,0] );     drawprimitive( gl.lines, [0,1,0,1], [ 0,-2,0, 0,2,0] );     drawprimitive( gl.lines, [0,0,1,1], [ 0,0,-2, 0,0,2] );     gl.linewidth(1);     if (leftcolors.length>0){     drawturtles(linecolors,moves,leftcolors,rightcolors,backcolors,bottoms,lefts,rights,backs,bottomns,leftns,rightns,backns);     } }

mat4.lookat(modelview, [0,0,6], [0,0,0], [0,1,0]) mat4.lookat(modelview, [0,0,6], [0,0,0], [0,1,0])

mat4.lookat(modelview, [0,0,8], [0,0,0], [0,1,0]) mat4.lookat(modelview, [0,0,8], [0,0,0], [0,1,0])

mat4.lookat(modelview, [0,0,4], [0,0,0], [0,1,0]) mat4.lookat(modelview, [0,0,4], [0,0,0], [0,1,0])

the problem comes clipping distance set mat4.ortho:

enter image description here

mat4.lookat(modelview, [0,0,8], [0,0,0], [0,1,0])

this set eye position such far plane pass thru (0,0,0), limiting viewable content view plane on (0,0,0).

mat4.lookat(modelview, [0,0,4], [0,0,0], [0,1,0])

this set eye pos @ limit of near plane, giving unpredictable results when equal.

so solution adjust near , far clipping in mat4.ortho:

mat4.ortho(projection,-2.5, 2.5, -2.5, 2.5, 4 - x, 8 + x);

where x minimal displacement.


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