几个OpenGL函数（glRectf() 像素重叠的处理方案）

69 阅读 0 评论 46 点赞

我是靠谱客的博主认真煎饼，最近开发中收集的这篇文章主要介绍几个OpenGL函数（glRectf() 像素重叠的处理方案），觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

2019独角兽企业重金招聘Python工程师标准>>>

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(factor, bias);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_FILL, GL_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.