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example: MultiCanvas show case with GL backend

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Change the MultiCanvas code to show how to render the content of
GlCanvas to a given off-screen framebuffer.

issue: https://github.com/thorvg/thorvg/issues/2746
This commit is contained in:
RuiwenTang 2024-09-27 22:57:31 +08:00 • committed by Hermet Park
parent e59c6046ec
commit 64df0791df
1 changed files with 110 additions and 5 deletions
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115
examples/MultiCanvas.cpp
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@ -22,6 +22,10 @@
#include "Example.h"
#ifdef THORVG_GL_RASTER_SUPPORT
#include <SDL2/SDL_opengl.h>
#endif
#define WIDTH 1024
#define HEIGHT 1024
#define NUM_PER_LINE 4
@ -88,6 +92,10 @@ void mainloop()
}
/************************************************************************/
/* SW Engine Specific Setup */
/************************************************************************/
void runSw()
{
auto window = SDL_CreateWindow("ThorVG Example (Software)", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, WIDTH, HEIGHT, SDL_WINDOW_HIDDEN);
@ -111,24 +119,115 @@ void runSw()
}
/************************************************************************/
/* GL Engine Specific Setup */
/************************************************************************/
#ifdef THORVG_GL_RASTER_SUPPORT
typedef void (*PFNGLTEXIMAGE2DPROC)(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid* pixels);
typedef void (*PFNGLTEXPARAMETERIPROC)(GLenum target, GLenum pname, GLint param);
PFNGLBINDTEXTUREEXTPROC fglBindTexture = nullptr;
PFNGLDELETETEXTURESEXTPROC fglDeleteTextures = nullptr;
PFNGLGENTEXTURESEXTPROC fglGenTextures = nullptr;
PFNGLTEXIMAGE2DPROC fglTexImage2D = nullptr;
PFNGLTEXPARAMETERIPROC fglTexParameteri = nullptr;
PFNGLGENFRAMEBUFFERSPROC fglGenFramebuffers = nullptr;
PFNGLBINDFRAMEBUFFERPROC fglBindFramebuffer = nullptr;
PFNGLDELETEFRAMEBUFFERSPROC fglDeleteFramebuffers = nullptr;
PFNGLFRAMEBUFFERTEXTURE2DPROC fglFramebufferTexture2D = nullptr;
PFNGLBLITFRAMEBUFFERPROC fglBlitFramebuffer = nullptr;
/* A helper class to manage OpenGL FrameBuffer creation and deletion
Also provides a simple way to flush the framebuffer to the screen at given position */
struct GLFrameBuffer
{
GLuint fbo;
GLuint texture;
~GLFrameBuffer()
{
if (fbo) fglDeleteFramebuffers(1, &fbo);
if (texture) fglDeleteTextures(1, &texture);
}
GLFrameBuffer(uint32_t width, uint32_t height)
{
fglGenFramebuffers(1, &fbo);
fglBindFramebuffer(GL_FRAMEBUFFER, fbo);
fglGenTextures(1, &texture);
fglBindTexture(GL_TEXTURE_2D, texture);
fglTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_BGRA, GL_UNSIGNED_BYTE, nullptr);
fglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
fglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
fglFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
fglBindFramebuffer(GL_FRAMEBUFFER, 0);
fglBindTexture(GL_TEXTURE_2D, 0);
}
void blitToScreen(uint32_t posX, uint32_t posY, uint32_t width, uint32_t height)
{
/* As this is a simple example, we will just blit the framebuffer to the screen
For a real application, you should use a shader to sample the texture and draw to the screen */
fglBindFramebuffer(GL_READ_FRAMEBUFFER, fbo);
fglBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
fglBlitFramebuffer(0, 0, width, height, posX, posY, posX +width, posY + height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
}
};
#endif
void runGl()
{
#if 1
cout << "Not Support OpenGL" << endl;
#else //TODO with FBO Target?
#ifdef THORVG_GL_RASTER_SUPPORT
#ifdef THORVG_GL_TARGET_GLES
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
#else
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
#endif
auto window = SDL_CreateWindow("ThorVG Example (OpenGL)", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, WIDTH, HEIGHT, SDL_WINDOW_OPENGL | SDL_WINDOW_HIDDEN);
auto context = SDL_GL_CreateContext(window);
fglBindTexture = (PFNGLBINDTEXTUREEXTPROC)SDL_GL_GetProcAddress("glBindTexture");
fglDeleteTextures = (PFNGLDELETETEXTURESEXTPROC)SDL_GL_GetProcAddress("glDeleteTextures");
fglGenTextures = (PFNGLGENTEXTURESEXTPROC)SDL_GL_GetProcAddress("glGenTextures");
fglTexImage2D = (PFNGLTEXIMAGE2DPROC)SDL_GL_GetProcAddress("glTexImage2D");
fglTexParameteri = (PFNGLTEXPARAMETERIPROC)SDL_GL_GetProcAddress("glTexParameteri");
fglBindFramebuffer = (PFNGLBINDFRAMEBUFFERPROC)SDL_GL_GetProcAddress("glBindFramebuffer");
fglGenFramebuffers = (PFNGLGENFRAMEBUFFERSPROC)SDL_GL_GetProcAddress("glGenFramebuffers");
fglDeleteFramebuffers = (PFNGLDELETEFRAMEBUFFERSPROC)SDL_GL_GetProcAddress("glDeleteFramebuffers");
fglFramebufferTexture2D = (PFNGLFRAMEBUFFERTEXTURE2DPROC)SDL_GL_GetProcAddress("glFramebufferTexture2D");
fglBlitFramebuffer = (PFNGLBLITFRAMEBUFFERPROC)SDL_GL_GetProcAddress("glBlitFramebuffer");
// Create the framebuffer which the GlCanvas can render to
// Since the example is just a simple demo, and only run the rendering function once
// we can just create one framebuffer
GLFrameBuffer glFbo{SIZE, SIZE};
for (int counter = 0; counter < NUM_PER_LINE * NUM_PER_LINE; ++counter) {
auto canvas = tvg::GlCanvas::gen();
//Set the canvas target and draw on it.
tvgexam::verify(canvas->target(0, WIDTH, HEIGHT));
// Pass the framebuffer id to the GlCanvas
tvgexam::verify(canvas->target(glFbo.fbo, SIZE, SIZE));
content(canvas.get());
if (tvgexam::verify(canvas->draw())) {
tvgexam::verify(canvas->sync());
}
// After the GlCanvas::sync() function, the content is rendered to the framebuffer
// The texture is now ready to be blit to the screen
auto y = (counter / NUM_PER_LINE) * SIZE;
auto x = (counter % NUM_PER_LINE) * SIZE;
glFbo.blitToScreen(x, y, SIZE, SIZE);
// After the framebuffer is blit to the screen, the framebuffer and texture can be reused in the next iteration
}
SDL_ShowWindow(window);
@ -138,10 +237,16 @@ void runGl()
SDL_GL_DeleteContext(context);
SDL_DestroyWindow(window);
#else
cout << "Not Support OpenGL" << endl;
#endif
}
/************************************************************************/
/* WG Engine Specific Setup */
/************************************************************************/
void runWg()
{
#if 1