Ma question est de savoir comment accélérer le dessin sur OpenGL sous Windows.Comment accélérer le dessin avec Cairo sur les fenêtres Opengl?
Le code de test est ci-dessous. Je l'ai copié à partir d'un exemple de cairo sur le web.
les fps tombent à 30 à 40 par seconde, encore plus lentement qu'un navigateur Web. Il suffit de dessiner la ligne chaque image, j'ai essayé d'écrire javascript sur html5. La même fonction dessine juste une ligne, et elle court beaucoup plus vite.
Pourquoi le caire dessine-t-il une ligne si ouverte? Est-ce que j'ai fait quelque chose de mal? et comment puis-je l'accélérer?
Je pense que C++ devrait être beaucoup plus rapide que le javascript
#include <stdlib.h>
#include <stdio.h>
#include <malloc.h>
#define _USE_MATH_DEFINES
#include <math.h>
#include <iostream>
#include <chrono>
#include <random>
#include <gl/glut.h>
#include <gl/glext.h>
#include <cairo.h>
using namespace std;
double win_width = 800;
double win_height = 600;
double hw = win_width/2;
double hh = win_height/2;
double line_width = 1;
//double line_width = 1/win_width;
cairo_surface_t * surf = NULL;
cairo_t * cr = NULL;
unsigned char * surf_data = NULL;
GLuint texture_id;
// Interface //
void opengl_init(void)
{
printf("OpenGL version: %s\n", glGetString(GL_VERSION));
printf("OpenGL vendor: %s\n", glGetString(GL_VENDOR));
printf("OpenGL renderer: %s\n", glGetString(GL_RENDERER));
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glDisable(GL_DEPTH_TEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_TEXTURE_RECTANGLE_ARB);
}
void opengl_cleanup(void)
{
glDeleteTextures(1, &texture_id);
}
void opengl_draw(int width, int height, unsigned char * surf_data)
{
if (!surf_data)
{
printf("draw_func() - No valid pointer to surface-data passed\n");
return;
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, texture_id);
glTexImage2D(GL_TEXTURE_RECTANGLE_ARB,
0,
GL_RGBA,
width,
height,
0,
GL_BGRA,
GL_UNSIGNED_BYTE,
surf_data);
glColor3f(0.25f, 0.5f, 1.0f);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f);
glVertex2f(0.0f, 0.0f);
glTexCoord2f((GLfloat)width, 0.0f);
glVertex2f(1.0f, 0.0f);
glTexCoord2f((GLfloat)width, (GLfloat)height);
glVertex2f(1.0f, 1.0f);
glTexCoord2f(0.0f, (GLfloat)height);
glVertex2f(0.0f, 1.0f);
glEnd();
glPopMatrix();
}
void opengl_resize(int width, int height)
{
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0f, 1.0f, 0.0f, 1.0f, -1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glDeleteTextures(1, &texture_id);
glGenTextures(1, &texture_id);
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, texture_id);
glTexImage2D(GL_TEXTURE_RECTANGLE_ARB,
0,
GL_RGBA,
width,
height,
0,
GL_BGRA,
GL_UNSIGNED_BYTE,
NULL);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
}
void drawShape()
{
//save current brush
cairo_save(cr);
// clear background
cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
//cairo_scale(cr, (double)win_height/1.0f, (double)win_height/1.0f);
cairo_set_source_rgba(cr, 1, 1, 1, 1);
cairo_paint(cr);
//set line color and style
cairo_set_line_cap(cr, CAIRO_LINE_CAP_ROUND);
cairo_set_line_width(cr, line_width);
static double angle = 0;
angle += 0.01f;
//draw rect
cairo_set_source_rgba(cr, 1, 0, 0, 1);
//cairo_rectangle(cr, 0.5f + sinf(angle) * 0.1f, 0.5f, 0.1f, 0.1f);
cairo_rectangle(cr, hw + sin(angle) * 100, hh, 100, 100);
cairo_fill(cr);
cairo_stroke(cr);
//draw circle
cairo_set_source_rgba(cr, 0, 0, 1, 1);
cairo_arc(cr, 300, hh, 100, 0, 2 * M_PI);
//cairo_fill(cr);
cairo_stroke(cr);
//draw line
static double r = 100;
static double posx = 500;
static double posy = 500;
static double x = 0;
static double y = 0;
x = r * cosf(angle);
y = r * sinf(angle);
cairo_set_source_rgba(cr, 0, 1, 0, 1);
cairo_move_to(cr, x + posx, y + posy);
cairo_line_to(cr, -x + posx, -y + posy);
cairo_stroke(cr);
int minx = 5;
int maxx = win_width - 5;
int miny = 5;
int maxy = win_height - 5;
int n = 50 * 2;
std::default_random_engine randomEngine;
randomEngine.seed(std::chrono::steady_clock::now().time_since_epoch().count());
std::uniform_real_distribution<float> rangeX(minx, maxx);
std::uniform_real_distribution<float> rangeY(miny, maxy);
cairo_set_source_rgba(cr, 0, 0, 0, 1);
for (int i = 0; i < n * 2; i += 4)
{
float x1 = rangeX(randomEngine);
float y1 = rangeY(randomEngine);
float x2 = rangeX(randomEngine);
float y2 = rangeY(randomEngine);
cairo_move_to(cr, x1, y1);
cairo_line_to(cr, x2, y2);
}
cairo_stroke(cr);
//restore previous brush
cairo_restore(cr);
}
void display(void)
{
static int fps = 0;
static int frame = 0;
static long long startTime = chrono::system_clock::now().time_since_epoch().count();
static long long lastTime = 2;
long long now = chrono::system_clock::now().time_since_epoch().count();
++frame;
//update per second
if (now - lastTime > 10000000)
{
lastTime = now;
fps = frame;
frame = 0;
cout << fps << endl;
}
drawShape();
opengl_draw(win_width, win_height, surf_data);
glutSwapBuffers();
}
cairo_t*
create_cairo_context(int width,
int height,
int channels,
cairo_surface_t** surf,
unsigned char** buffer)
{
cairo_t* cr;
// create cairo-surface/context to act as OpenGL-texture source
*buffer = (unsigned char*)calloc(channels * width * height, sizeof(unsigned char));
if (!*buffer)
{
printf("create_cairo_context() - Couldn't allocate buffer\n");
return NULL;
}
*surf = cairo_image_surface_create_for_data(*buffer,
CAIRO_FORMAT_ARGB32,
width,
height,
channels * width);
if (cairo_surface_status(*surf) != CAIRO_STATUS_SUCCESS)
{
free(*buffer);
printf("create_cairo_context() - Couldn't create surface\n");
return NULL;
}
cr = cairo_create(*surf);
if (cairo_status(cr) != CAIRO_STATUS_SUCCESS)
{
free(*buffer);
printf("create_cairo_context() - Couldn't create context\n");
return NULL;
}
return cr;
}
void cleanup(void)
{
opengl_cleanup();
free(surf_data);
cairo_destroy(cr);
exit(0);
}
void keyboard(unsigned char key, int x, int y)
{
switch (key)
{
//27 is ESC key
case 27:
case 'q':
cleanup();
break;
case 'd':
cairo_surface_write_to_png(surf, "frame.png");
break;
case '+':
if (line_width < 10)
line_width += 1;
break;
case '-':
if (line_width > 1)
line_width -= 1;
break;
}
}
void idle(void)
{
glutPostRedisplay();
}
int main(int argc, char ** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowSize(win_width, win_height);
if (glutCreateWindow("Opengl Test") == 0)
exit(-2);
// create cairo-surface/context to act as OpenGL-texture source
cr = create_cairo_context(win_width, win_height, 4, &surf, &surf_data);
// setup "GL-context"
opengl_init();
glutDisplayFunc(display);
glutKeyboardFunc(keyboard);
glutIdleFunc(idle);
opengl_resize(win_width, win_height);
glutMainLoop();
return 0;
}
et voici le code html et js i utilisent
index.html
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript" src="main.js"></script>
<style type="text/css">
html, body {
margin: 0px;
}
canvas {
display: block;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
</body>
</html>
main.js
window.onload = function() {
var canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
width = canvas.width = window.innerWidth,
height = canvas.height = window.innerHeight;
render();
function render() {
context.clearRect(0, 0, width, height);
for(var i = 0; i < 100; i += 1){
context.beginPath();
context.moveTo(Math.random() * width, Math.random() * height);
context.lineTo(Math.random() * width, Math.random() * height);
context.stroke();
}
requestAnimationFrame(render);
}
};
Merci, datenwolf.Je ne suis pas un anglophone natif, que voulez-vous dire - Idéalement, vous utiliseriez un backend accéléré OpenGL pour Cairo? Je n'ai trouvé aucune description ou lien de cette page opengl backend accéléré dois-je utiliser exactement? – kileyi
Je veux juste dessiner environ 512 - 1024 lignes chaque image sur Opengl, mieux vaut dessiner vectoriel, donc j'ai essayé Cairo, j'ai entendu cairo dessiner sur beaucoup de contexte, donc je l'essaie juste. N'a pas réalisé CPU ou GPU les usages.Mais je ne suis pas limité à Cario seulement, je vais essayer NanoVG maintenant, voir s'il peut dessiner rapidement 1024 lignes par image – kileyi
OK, essayé NanoVG avec 3000 lignes par seconde sur l'exemple gl3, 100 + fps pour mon ordinateur, Je suis plutôt content du résultat, merci encore, je pense que je vais utiliser NanoVG à la place :) – kileyi