我的世界中的OpenGL绘图四边形怪异地显示 [英] OpenGL Drawing quads in minecraft display weirdly

问题描述

我正在尝试在Minecraft中绘制四边形，但这是我遇到的问题: http://imgur.com/DgnAqv1 ，但是它应该在每边绘制一个三角形，所以总共应该有4个三角形，我不知道为什么这不起作用.

Im trying to draw some quads in minecraft but this is the problem im having: http://imgur.com/DgnAqv1 but it should draw triangles on each sides so there should be 4 triangles in total, I dont know why this isnt working.

GL11.glPushMatrix();
GL11.glDisable(GL11.GL_LIGHTING);
GL11.glDisable(GL11.GL_DEPTH_TEST);
GL11.glDepthMask(false);
GL11.glEnable(GL11.GL_BLEND);
GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
GL11.glColor4f(0F, 0.5F, 0.8F, 1F);
GL11.glBegin(GL11.GL_QUADS);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX + 1, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ + 1);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glEnd();
GL11.glBegin(GL11.GL_QUADS);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX - 1, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ - 1);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glEnd();
GL11.glBegin(GL11.GL_QUADS);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX - 1, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ + 1);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glEnd();
GL11.glBegin(GL11.GL_QUADS);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX + 1, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ - 1);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glEnd();
GL11.glEnable(GL11.GL_DEPTH_TEST);
GL11.glDepthMask(true);
GL11.glPopMatrix();

推荐答案

您可能应该禁用面剔除:GL11.glDisable(GL11.GL_CULL_FACE);您的三角形方向可能错误，因此只能看到背面.另一个解决方案是重新排列三角形的方向(例如，通过交换第一个和第二个顶点)，但是由于使用透明性，您可能要同时渲染正面和背面.

You should probably disable face culling: GL11.glDisable(GL11.GL_CULL_FACE); Your triangles might have the wrong orientation, so you only see the back faces. Another solution would be to reorient the triangles (e.g. by swapping the first and second vertex), but since you use transparency you probably want to render both front and back faces.

侧面说明:如果要渲染三角形，我不知道为什么要使用GL_QUADS.这是您发布的第一个四边形:

Side note: I don't know why you're using GL_QUADS if you want to render triangles. So here's the first quad you posted:

GL11.glBegin(GL11.GL_QUADS);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX + 1, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ + 1);
GL11.glVertex3d(ep.posX - RenderManager.renderPosX, ep.posY + ep.height + 0.5D - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ);
GL11.glEnd();

使用glTranslate和GL_TRIANGLES的等效代码为:

The equivalent code using glTranslate and GL_TRIANGLES would be:

GL11.glTranslated(ep.posX - RenderManager.renderPosX, ep.posY - RenderManager.renderPosY, ep.posZ - RenderManager.renderPosZ );
GL11.glBegin(GL11.GL_TRIANGLES);
GL11.glVertex3d(0, ep.height + 0.5D, 0);
GL11.glVertex3d(1, 0, 0);
GL11.glVertex3d(0, 0, 1);
GL11.glEnd();

还请注意，您不需要为每个三角形调用glBegin/glEnd，只需调用glVertex3d 3 * n次即可渲染n个三角形.

Also note that you don't need to call glBegin/glEnd for each triangle, you can simply call glVertex3d 3*n times to render n triangles.

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