几个OpenGL函数(glRectf() 像素重叠的处理方案)

2014/06/20 18:00
阅读数 2K

glRectf(glfloat x1,glfloat y1,glfloat x2,glfloat y2):x1,y1指定矩形的一个顶点x2,y2指定矩形反方向的顶点。四个点严格等于下面的序列(x1,y1)(x2,y1)(x2,y2)(x1,y2)。如果第二个顶点在第一个顶点的上方和右侧,那么这个矩形将以逆时针旋转方向构造

glRectf(const glfloat *v1,const glfloat *v2):v1一个指向矩形的一个顶点的指针,v2一个指向矩形的一个顶点的指针

 


像素重叠的解决方案;

在渲染环境设置中加入以下两条语句:

glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(1.0f, 0.0f);

glPolygonOffset(factorbias);offset的计算公式是factor * DZ + bias

http://www.opengl.org/sdk/docs/man/html/glPolygonOffset.xhtml

Name

glPolygonOffset — set the scale and units used to calculate depth values

C Specification

void glPolygonOffset( GLfloat factor,

GLfloat units);

 

Parameters

  • factor

  • Specifies a scale factor that is used to create a variable depth offset for each polygon. The initial value is 0.

  • units

  • Is multiplied by an implementation-specific value to create a constant depth offset. The initial value is 0.

Description

When GL_POLYGON_OFFSET_FILLGL_POLYGON_OFFSET_LINE, or GL_POLYGON_OFFSET_POINT is enabled, each fragment's depth value will be offset after it is interpolated from the depth values of the appropriate vertices. The value of the offset is factor×DZ+r×units, where DZ is a measurement of the change in depth relative to the screen area of the polygon, and r is the smallest value that is guaranteed to produce a resolvable offset for a given implementation. The offset is added before the depth test is performed and before the value is written into the depth buffer.

glPolygonOffset is useful for rendering hidden-line images, for applying decals to surfaces, and for rendering solids with highlighted edges.

Associated Gets

glIsEnabled with argument GL_POLYGON_OFFSET_FILLGL_POLYGON_OFFSET_LINE, or GL_POLYGON_OFFSET_POINT.

glGet with argument GL_POLYGON_OFFSET_FACTOR or GL_POLYGON_OFFSET_UNITS.

See Also

glDepthFuncglEnableglGetglIsEnabled

Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2013 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.



展开阅读全文
打赏
0
1 收藏
分享
加载中
更多评论
打赏
0 评论
1 收藏
0
分享
返回顶部
顶部