What are WebGL's draw primitives?

问题

I've been doing some graphics programming using webgl to draw OBJMesh's, but it hasn't gone too well as it is not drawing it correctly. I think thats because of the drawing primitives that I'm using e.g : gl.drawArrays(gl.TRIANGLE_STRIP, 0, vertexBuffer.numItems);

So can I ask what primitives do webGL allow? is it the same as openGL? I've been trying to use gl.QUADS as I thought it would allow it as openGL does, so I'm not too sure anymore.

回答1:

From https://www.khronos.org/registry/webgl/specs/1.0/:

const GLenum POINTS                         = 0x0000;
const GLenum LINES                          = 0x0001;
const GLenum LINE_LOOP                      = 0x0002;
const GLenum LINE_STRIP                     = 0x0003;
const GLenum TRIANGLES                      = 0x0004;
const GLenum TRIANGLE_STRIP                 = 0x0005;
const GLenum TRIANGLE_FAN                   = 0x0006;

回答2:

Yes, WebGL draws the same primitives as OpenGL ES (same also as OpenGL). Have you tried drawing some trivial meshes so you can narrow down what the problem could be? Are you setting culling, drawing the right primitive, etc.?

I've done a few WebGL demos where I draw complex meshes, and I always use GL_TRIANGLES (TRIANGLES). If I try the same meshes with other primitives, it breaks the mesh, so it depends how the mesh was created.

Here are my demos http://rodrigo-silveira.com/webgl-3d-demos/

来源：https://stackoverflow.com/questions/14503600/what-are-webgls-draw-primitives