OpenGL Shading Language (3)

Posted on 2017/06/13, 9:56 PM By admin22

今回はWayland EGLの環境で、前回の四面体を表示してみました。

WaylandはXに変わるディスプレイサーバで、以下の記事でFedora25(デフォルトでサポート)上でテストしました。

Wayland Display Server

ここでは、Ubuntu 16.04を使います。(インストールメモを忘れてしましまたが、下にあるコンパイルオプションからだいたい想像できると思います)

参考 :
http://blog.techlab-xe.net/archives/4637
https://github.com/techlabxe/SimpleWindowWayland/tree/base-1.1

こちらのサイトを参考にさせていただきました。
カメラが自動的移動する処理はそのままで、四面体を表示させ色をつけています。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <cmath>
#include <cstdint>
#include <vector>
#include <GLES2/gl2.h>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <glm/gtc/matrix_transform.hpp>

#include "WaylandCore.h"

#define WIDTH 640
#define HEIGHT 480
#define TITLE  "Wayland EGL Window"

const GLchar* srcVertexShader[] =
{
	"attribute vec4 vPosition;\n"
	"attribute vec3 vColor;\n"
	"varying vec4 color;\n"
	"uniform vec4 matPVW[4];\n"
	"void main() {\n"
		"vec4 pos;\n"
		"pos = matPVW[0] * vPosition.x;\n"
		"pos += matPVW[1]* vPosition.y;\n"
		"pos += matPVW[2]* vPosition.z;\n"
		"pos += matPVW[3]* vPosition.w;\n"
		"gl_Position = pos;\n"
		"color.rgb = vec3(vColor.r, vColor.g, vColor.b);\n"
		"color.a = 1.0;\n"
	"}"
};

const GLchar* srcFragmentShader[] =
{
	"precision mediump float; \n"
	"varying vec4 color;\n"
	"void main() {\n"
		"gl_FragColor = color;\n"
	"}"
};

struct DrawBatch {
	GLuint vb, ib;
	GLuint shader;
	int indexCount;
} drawObj;

struct VertexPosition {
	float x, y, z;
};
struct VertexColor {
	float r, g, b;
};
struct Vertex {
	VertexPosition Position;
	VertexColor   Color;
};

GLint attrPVW;

GLuint createShaderProgram(const char* srcVS[], const char* srcFS[]){
	GLuint shaderVS = glCreateShader(GL_VERTEX_SHADER);
	GLuint shaderFS = glCreateShader(GL_FRAGMENT_SHADER);

	glShaderSource(shaderVS, 1, srcVS, NULL);
	glCompileShader(shaderVS);

	glShaderSource(shaderFS, 1, srcFS, NULL);
	glCompileShader(shaderFS);

	GLuint program;
	program = glCreateProgram();
	glAttachShader(program, shaderVS);
	glAttachShader(program, shaderFS);

	glLinkProgram(program);

	return program;
}

template<typename T> GLuint createBufferObject(std::vector<T>& src, GLuint type)
{
	GLuint vbo;
	glGenBuffers( 1, &vbo );
	glBindBuffer( type, vbo );
	glBufferData( type, sizeof(T) * src.size(), src.data(), GL_STATIC_DRAW );
	return vbo;
}

void createResource() {
	drawObj.shader = createShaderProgram( srcVertexShader, srcFragmentShader );
	GLint attrPos = glGetAttribLocation( drawObj.shader, "vPosition" );
	GLint attrCol = glGetAttribLocation( drawObj.shader, "vColor" );
	
	attrPVW = glGetUniformLocation( drawObj.shader, "matPVW" );

	std::vector<uint16_t> indices = {0,1,2,1,2,3,0,2,3,0,1,3};
	std::vector<Vertex> vertices;

	GLfloat vData[] = { 
		-1.0f, -1.0f, 0.0f, //1
		 1.0f, -1.0f, 0.0f, //2
		 0.0f,  1.0f, 0.0f, //3
		 0.0f,  0.0f, 1.0f, //4
	};
	GLfloat vColor[] = {
		1.0f, 0.0f, 0.0f,
		0.0f, 1.0f, 0.0f,
		0.0f, 0.0f, 1.0f,
		1.0f, 1.0f, 1.0f,
	};
	
	for(int i=0;i<4;i++){
		Vertex v;
		v.Position.x = vData[i*3];
		v.Position.y = vData[i*3+1];
		v.Position.z = vData[i*3+2];
		v.Color.r = vColor[i*3];
		v.Color.g = vColor[i*3+1];
		v.Color.b = vColor[i*3+2];
		vertices.push_back(v);
	}
	drawObj.vb = createBufferObject(vertices, GL_ARRAY_BUFFER);
	drawObj.ib = createBufferObject(indices, GL_ELEMENT_ARRAY_BUFFER);
	drawObj.indexCount = indices.size();

	char* offset = NULL;
	int stride = sizeof(Vertex);
	
	glVertexAttribPointer(attrPos, 3, GL_FLOAT, GL_FALSE, stride, offset);
	offset += sizeof(VertexPosition);
	glVertexAttribPointer(attrCol, 3, GL_FLOAT, GL_FALSE, stride, offset);
	offset += sizeof(VertexColor);
	
	glEnableVertexAttribArray(attrPos);
	glEnableVertexAttribArray(attrCol);
}

void destroyResource() {
	glDeleteBuffers( 1, &drawObj.vb );
	glDeleteBuffers( 1, &drawObj.ib );
	glDeleteProgram( drawObj.shader );
}

void draw()
{
	static double angle = 0.0f;
	angle += .01f;
	if( angle > 3600.0 ) {
		angle -= 3600.0;
	}
	
	glEnable(GL_DEPTH_TEST);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	
	glm::vec3 cameraPos = glm::vec3(0.0, 0.0f, 2.0f);
	glm::mat4 proj = glm::perspective<float>(30.0f, float(WIDTH)/float(HEIGHT), 1.0f, 100.0f);
	glm::mat4 view = glm::lookAt<float>(cameraPos, glm::vec3(0.0f,0.0f,0.0f), glm::vec3(0.0f,1.0f,0.0f));
	glm::mat4 world= glm::rotate( glm::mat4(1.0f), (float)angle, glm::vec3(0.0f,0.0f,1.0f));
	world= glm::rotate(world, (float) angle * 0.5f, glm::vec3(0.0f, 0.0f, 1.0f));
	world= glm::rotate(world, (float) angle * 0.5f, glm::vec3(1.0f, 0.0f, 0.0f));
	glUseProgram(drawObj.shader);

	glm::mat4 pvw = proj * view * world;
	glUniform4fv(attrPVW, 4, glm::value_ptr(pvw));
	glBindBuffer(GL_ARRAY_BUFFER, drawObj.vb);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, drawObj.ib);
	glDrawElements(GL_TRIANGLES, drawObj.indexCount, GL_UNSIGNED_SHORT, NULL);   
}

int main() {
	WaylandCore* core = new WaylandCore(WIDTH, HEIGHT, TITLE);

	fprintf(stderr, "Renderer: %s\n", (char*)glGetString(GL_RENDERER));
	fprintf(stderr, "GL_VERSION: %s\n", (char*)glGetString( GL_VERSION));
	fprintf(stderr, "GL_EXTENSIONS: %s\n", (char*)glGetString(GL_EXTENSIONS));

	createResource();
  
	while( !core->isShouldClose() ) {
		core->pollEvents();
		usleep(100*1000);
		
		glClearColor( 0, 0, 0.25f, 0.75f );
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
		
		draw();
		
		core->swapBuffers();
	}
	
	destroyResource();
	
	delete core;core = NULL;
	return 0;
}

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#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <cmath>

#include <cstdint>

#include <vector>

#include <GLES2/gl2.h>

#include <glm/glm.hpp>

#include <glm/gtc/type_ptr.hpp>

#include <glm/gtc/matrix_transform.hpp>

#include "WaylandCore.h"

#define WIDTH 640

#define HEIGHT 480

#define TITLE "Wayland EGL Window"

const GLchar* srcVertexShader[] =

{

"attribute vec4 vPosition;\n"

"attribute vec3 vColor;\n"

"varying vec4 color;\n"

"uniform vec4 matPVW[4];\n"

"void main() {\n"

"vec4 pos;\n"

"pos = matPVW[0] * vPosition.x;\n"

"pos += matPVW[1]* vPosition.y;\n"

"pos += matPVW[2]* vPosition.z;\n"

"pos += matPVW[3]* vPosition.w;\n"

"gl_Position = pos;\n"

"color.rgb = vec3(vColor.r, vColor.g, vColor.b);\n"

"color.a = 1.0;\n"

"}"

};

const GLchar* srcFragmentShader[] =

{

"precision mediump float; \n"

"varying vec4 color;\n"

"void main() {\n"

"gl_FragColor = color;\n"

"}"

};

struct DrawBatch {

GLuint vb, ib;

GLuint shader;

int indexCount;

} drawObj;

struct VertexPosition {

float x, y, z;

};

struct VertexColor {

float r, g, b;

};

struct Vertex {

VertexPosition Position;

VertexColor Color;

};

GLint attrPVW;

GLuint createShaderProgram(const char* srcVS[], const char* srcFS[]){

GLuint shaderVS = glCreateShader(GL_VERTEX_SHADER);

GLuint shaderFS = glCreateShader(GL_FRAGMENT_SHADER);

glShaderSource(shaderVS, 1, srcVS, NULL);

glCompileShader(shaderVS);

glShaderSource(shaderFS, 1, srcFS, NULL);

glCompileShader(shaderFS);

GLuint program;

program = glCreateProgram();

glAttachShader(program, shaderVS);

glAttachShader(program, shaderFS);

glLinkProgram(program);

return program;

}

template<typename T> GLuint createBufferObject(std::vector<T>& src, GLuint type)

{

GLuint vbo;

glGenBuffers( 1, &vbo );

glBindBuffer( type, vbo );

glBufferData( type, sizeof(T) * src.size(), src.data(), GL_STATIC_DRAW );

return vbo;

}

void createResource() {

drawObj.shader = createShaderProgram( srcVertexShader, srcFragmentShader );

GLint attrPos = glGetAttribLocation( drawObj.shader, "vPosition" );

GLint attrCol = glGetAttribLocation( drawObj.shader, "vColor" );

attrPVW = glGetUniformLocation( drawObj.shader, "matPVW" );

std::vector<uint16_t> indices = {0,1,2,1,2,3,0,2,3,0,1,3};

std::vector<Vertex> vertices;

GLfloat vData[] = {

-1.0f, -1.0f, 0.0f, //1

1.0f, -1.0f, 0.0f, //2

0.0f, 1.0f, 0.0f, //3

0.0f, 0.0f, 1.0f, //4

};

GLfloat vColor[] = {

1.0f, 0.0f, 0.0f,

0.0f, 1.0f, 0.0f,

0.0f, 0.0f, 1.0f,

1.0f, 1.0f, 1.0f,

};

for(int i=0;i<4;i++){

Vertex v;

v.Position.x = vData[i*3];

v.Position.y = vData[i*3+1];

v.Position.z = vData[i*3+2];

v.Color.r = vColor[i*3];

v.Color.g = vColor[i*3+1];

v.Color.b = vColor[i*3+2];

vertices.push_back(v);

}

drawObj.vb = createBufferObject(vertices, GL_ARRAY_BUFFER);

drawObj.ib = createBufferObject(indices, GL_ELEMENT_ARRAY_BUFFER);

drawObj.indexCount = indices.size();

char* offset = NULL;

int stride = sizeof(Vertex);

glVertexAttribPointer(attrPos, 3, GL_FLOAT, GL_FALSE, stride, offset);

offset += sizeof(VertexPosition);

glVertexAttribPointer(attrCol, 3, GL_FLOAT, GL_FALSE, stride, offset);

offset += sizeof(VertexColor);

glEnableVertexAttribArray(attrPos);

glEnableVertexAttribArray(attrCol);

}

void destroyResource() {

glDeleteBuffers( 1, &drawObj.vb );

glDeleteBuffers( 1, &drawObj.ib );

glDeleteProgram( drawObj.shader );

}

void draw()

{

static double angle = 0.0f;

angle += .01f;

if( angle > 3600.0 ) {

angle -= 3600.0;

}

glEnable(GL_DEPTH_TEST);

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glm::vec3 cameraPos = glm::vec3(0.0, 0.0f, 2.0f);

glm::mat4 proj = glm::perspective<float>(30.0f, float(WIDTH)/float(HEIGHT), 1.0f, 100.0f);

glm::mat4 view = glm::lookAt<float>(cameraPos, glm::vec3(0.0f,0.0f,0.0f), glm::vec3(0.0f,1.0f,0.0f));

glm::mat4 world= glm::rotate( glm::mat4(1.0f), (float)angle, glm::vec3(0.0f,0.0f,1.0f));

world= glm::rotate(world, (float) angle * 0.5f, glm::vec3(0.0f, 0.0f, 1.0f));

world= glm::rotate(world, (float) angle * 0.5f, glm::vec3(1.0f, 0.0f, 0.0f));

glUseProgram(drawObj.shader);

glm::mat4 pvw = proj * view * world;

glUniform4fv(attrPVW, 4, glm::value_ptr(pvw));

glBindBuffer(GL_ARRAY_BUFFER, drawObj.vb);

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, drawObj.ib);

glDrawElements(GL_TRIANGLES, drawObj.indexCount, GL_UNSIGNED_SHORT, NULL);

}

int main() {

WaylandCore* core = new WaylandCore(WIDTH, HEIGHT, TITLE);

fprintf(stderr, "Renderer: %s\n", (char*)glGetString(GL_RENDERER));

fprintf(stderr, "GL_VERSION: %s\n", (char*)glGetString( GL_VERSION));

fprintf(stderr, "GL_EXTENSIONS: %s\n", (char*)glGetString(GL_EXTENSIONS));

createResource();

while( !core->isShouldClose() ) {

core->pollEvents();

usleep(100*1000);

glClearColor( 0, 0, 0.25f, 0.75f );

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

draw();

core->swapBuffers();

}

destroyResource();

delete core;core = NULL;

return 0;

}

g++ -o WaylandEglTest main.cpp WaylandCore.cpp WaylandCore_registry_handlers.cpp WaylandCore_seat_handlers.cpp -lwayland-client -lwayland-cursor -lwayland-egl -lEGL -lGLESv2 -std=c++11

main.cpp以外のWayland部分は、上記サイトにあるのを使わせていただきました。
(マウスやキーボードのイベントリスナーなども含んでいます)
参考までに、メインループの最初と最後にあるpollEvents()とswapBuffers()をWaylandCore.cppから抜粋。

void WaylandCore::pollEvents() {
  if( mDisplay == NULL || mRegistry == NULL ) {
    mShouldClose = true;
    return;
  }
  pollfd fds[] = {
    { wl_display_get_fd(mDisplay), POLLIN },
  };
  while( wl_display_prepare_read(mDisplay) != 0 )
  {
    wl_display_dispatch_pending(mDisplay);
  }
  wl_display_flush(mDisplay);
  if( poll(fds,1,0) > 0 )
  {
    wl_display_read_events(mDisplay);
    wl_display_dispatch_pending(mDisplay);
  } else {
    wl_display_cancel_read(mDisplay);
  }
}

void WaylandCore::swapBuffers()
{
  eglSwapBuffers( mEglDisplay, mSurface.eglSurface );
}

void WaylandCore::pollEvents() {

if( mDisplay == NULL || mRegistry == NULL ) {

mShouldClose = true;

return;

}

pollfd fds[] = {

{ wl_display_get_fd(mDisplay), POLLIN },

};

while( wl_display_prepare_read(mDisplay) != 0 )

{

wl_display_dispatch_pending(mDisplay);

}

wl_display_flush(mDisplay);

if( poll(fds,1,0) > 0 )

{

wl_display_read_events(mDisplay);

wl_display_dispatch_pending(mDisplay);

} else {

wl_display_cancel_read(mDisplay);

}

void WaylandCore::swapBuffers()

{

eglSwapBuffers( mEglDisplay, mSurface.eglSurface );

}

イベントのポーリングでソケット読み込みしています。IPC(Interprocess Communication)の部分が詳しく書かれています。OpneGLもそうですが、コードボリュームが多くなってしまうのは、このような細かいAPI(wl_xxx)を組みあわせるところから書くからでしょう。意味がわかれば中身を意識せず使えばいいと思われます。
(この部分、Xのようにリモートでアクセスできるかどうか、興味は膨らみます)

ここまで違う環境でシェーダープログラムを試してみると、理解がより深まった気がします。
いろいろな環境で実行できるとわかったところで、GPUの特性を生かした画像処理のシェーダプログラムにもっと比重をおいて学習したいと思います。

Renderer: Gallium 0.4 on llvmpipe(LLVM3.8, 256bits)
GL Version : OpenGL ES 3.0 Mesa 12.0.6
EGL major : 1 minor : 4

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