Question

我在绘制OpenGL时看POINT_SIZE但我现在确定如何访问常量来获取处理中的POINT_SIZE。

快速浏览Processing javadocs后，我尝试启用ALIASED_POINT_SIZE_RANGE，如下所示：

pgl.enable(PGL.ALIASED_POINT_SIZE_RANGE);

但是我收到了这个错误：

OpenGL error 1280 at top endDraw(): invalid enumerant

我尝试的只是修改示例中的LowLevelGL示例＆gt;演示＆gt;图形：

// Draws a triangle using low-level OpenGL calls.
import java.nio.*;

PGL pgl;
PShader sh;

int vertLoc;
int colorLoc;

float[] vertices;
float[] colors;

FloatBuffer vertData;
FloatBuffer colorData;

void setup() {
  size(640, 360, P3D);
  // Loads a shader to render geometry w/out
  // textures and lights.
  sh = loadShader("frag.glsl", "vert.glsl");

  vertices = new float[12];
  vertData = allocateDirectFloatBuffer(12);

  colors = new float[12];
  colorData = allocateDirectFloatBuffer(12);
}

void draw() {
  background(0);

  // The geometric transformations will be automatically passed 
  // to the shader.
  rotate(frameCount * 0.01, width, height, 0);

  updateGeometry();

  pgl = beginPGL();
  sh.bind();

  pgl.enable(PGL.ALIASED_POINT_SIZE_RANGE);

  vertLoc = pgl.getAttribLocation(sh.glProgram, "vertex");
  colorLoc = pgl.getAttribLocation(sh.glProgram, "color");

  pgl.enableVertexAttribArray(vertLoc);
  pgl.enableVertexAttribArray(colorLoc);

  pgl.vertexAttribPointer(vertLoc, 4, PGL.FLOAT, false, 0, vertData);
  pgl.vertexAttribPointer(colorLoc, 4, PGL.FLOAT, false, 0, colorData);

  pgl.drawArrays(PGL.TRIANGLES, 0, 3);

  pgl.disableVertexAttribArray(vertLoc);
  pgl.disableVertexAttribArray(colorLoc);

  sh.unbind();  

  endPGL();
}

void updateGeometry() {
  // Vertex 1
  vertices[0] = 0;
  vertices[1] = 0;
  vertices[2] = 0;
  vertices[3] = 1;
  colors[0] = 1;
  colors[1] = 0;
  colors[2] = 0;
  colors[3] = 1;

  // Corner 2
  vertices[4] = width/2;
  vertices[5] = height;
  vertices[6] = 0;
  vertices[7] = 1;
  colors[4] = 0;
  colors[5] = 1;
  colors[6] = 0;
  colors[7] = 1;

  // Corner 3
  vertices[8] = width;
  vertices[9] = 0;
  vertices[10] = 0;
  vertices[11] = 1;
  colors[8] = 0;
  colors[9] = 0;
  colors[10] = 1;
  colors[11] = 1;

  vertData.rewind();
  vertData.put(vertices);
  vertData.position(0);

  colorData.rewind();
  colorData.put(colors);
  colorData.position(0);  
}

FloatBuffer allocateDirectFloatBuffer(int n) {
  return ByteBuffer.allocateDirect(n * Float.SIZE/8).order(ByteOrder.nativeOrder()).asFloatBuffer();
}

vert.glsl：

/*
  Part of the Processing project - http://processing.org

  Copyright (c) 2011-12 Ben Fry and Casey Reas

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License version 2.1 as published by the Free Software Foundation.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General
  Public License along with this library; if not, write to the
  Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  Boston, MA  02111-1307  USA
 */

uniform mat4 transform;

attribute vec4 vertex;
attribute vec4 color;

varying vec4 vertColor;

void main() {
  gl_PointSize = 200.0;
  gl_Position = transform * vertex;    
  vertColor = color;
}

frag.glsl：

/*
  Part of the Processing project - http://processing.org

  Copyright (c) 2011-12 Ben Fry and Casey Reas

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License version 2.1 as published by the Free Software Foundation.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General
  Public License along with this library; if not, write to the
  Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  Boston, MA  02111-1307  USA
 */

#ifdef GL_ES
precision mediump float;
precision mediump int;
#endif

varying vec4 vertColor;

void main() {
  gl_FragColor = vertColor;
}

我明确的问题是我需要访问哪些Processing对象才能启用POINT_SIZE以及如何更改GLSL着色器的大小？

Answer 1

尝试检查您的上下文的OpenGL版本，因为在GL版本1.2及更高版本中不推荐使用 GL_POINT_SIZE_RANGE 和 GL_POINT_SIZE_GRANULARITY 。其功能已被 GL_SMOOTH_POINT_SIZE_RANGE 和 GL_SMOOTH_POINT_SIZE_GRANULARITY 取代。

如何使用GLSL在Processing 2.2.1中设置glPointSize？

1 个答案: