绘制多个重复的模型时,使用实例化方式绘制可以大大加快显然速度。
绘制效果如下图所示:
<强>
attribute vec3 pos;
attribute vec2 coord;
attribute vec3 正常;
attribute vec3 补偿;
uniform mat4 M;
uniform mat4 V;
uniform mat4 P;
uniform mat4 纳米;
varying vec2 M_coord;
varying vec3 M_normal;
varying vec4 M_WordPos;
void main ()
{
,,,,,,,M_coord =, coord;
,,,,,,,M_WordPos =, M *, vec4 (pos, 1.0), +, vec4(抵消,,1.0);
,,,,,,,M_normal =, mat3 (NM), *,正常;
,,,,,,,gl_Position =, P *, V *, M_WordPos;
} 偏移量为每次绘制的偏移量。
<强>
float nIndexOffset [],=, {
,,,,,,,-100.0 f, f 0.0,, 0.0度,
,,,,,,,0.0 f, f 0.0,, 0.0度,
,,,,,,,100.0 f, f 0.0, 0.0度
,,,}, createBufferObject为封装创建OpenGL缓冲区的函数
定义如下:
GLuint OpenGLOperate:: createBufferObject (GLenum nBufferType, GLsizeiptr 大小,,\
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,const GLvoid *数据,GLenum 使用)
{
,,,GLuint BufferObjIndex =, 0;
,,,m_OpenGLCore→glGenBuffers(1),和BufferObjIndex);
,,,m_OpenGLCore→glBindBuffer (BufferObjIndex nBufferType也);
,,,m_OpenGLCore→glBufferData (nBufferType、,大小,数据,使用);
,,,m_OpenGLCore→glBindBuffer (nBufferType, 0);
,,,return BufferObjIndex;
} 创建抵消的反馈
m_OffsetIndex =, m_OpenGLOperate→createBufferObject (GL_ARRAY_BUFFER,, \
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,sizeof(浮动),*,9日\
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,(void *) nIndexOffset, GL_STATIC_DRAW); 为抵消赋值
OpenGLCore→glBindBuffer (m_OffsetIndex GL_ARRAY_BUFFER也);
OpenGLCore→glEnableVertexAttribArray (m_OffsetLocation);
OpenGLCore→glVertexAttribPointer (m_OffsetLocation,, 3,, GL_FLOAT,, GL_FALSE,, \
sizeof(浮动),*,3,(void *) 0);
OpenGLCore→glBindBuffer (GL_ARRAY_BUFFER, 0);
OpenGLCore→glVertexAttribDivisor (m_OffsetLocation, 1); 调用绘制指令:
OpenGLCore→glDrawElementsInstanced (m_VertexCount, GL_TRIANGLES, \
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,GL_UNSIGNED_INT 0,, 3);
