From 22e1a81574f25077e3f04265ce29122f4dfa14ef Mon Sep 17 00:00:00 2001
From: caoxiong <caoxiong@vector4d.cn>
Date: Tue, 26 Nov 2024 18:29:46 +0800
Subject: [PATCH] fix simple-es2 to save back buffer to disk

---
 src/simple-es2.c | 55 ++++++++++++++++++++++++++++--------------------
 1 file changed, 32 insertions(+), 23 deletions(-)

diff --git a/src/simple-es2.c b/src/simple-es2.c
index 43fedf1..07b75ab 100644
--- a/src/simple-es2.c
+++ b/src/simple-es2.c
@@ -17,6 +17,7 @@
 #include <stdbool.h>
 #include <threads.h>
 
+#include <sys/time.h>
 #include <signal.h>
 
 #include "GLES2/gl2.h"
@@ -53,6 +54,9 @@ GLuint       g_hProjMatrixLoc      = 0;
 GLuint       g_hVertexLoc          = 0;
 GLuint       g_hColorLoc           = 1;
 
+int fbo_width = 800;
+int fbo_height = 600;
+
 #define ASSERT_EQ(exp1, exp2) do { auto e1 = (exp1);auto e2 = (exp2);\
  if((e1) != (e2)) { \
     printf("assert value: %p, %p\n", e1, e2); \
@@ -116,7 +120,7 @@ float VertexPositions[] =
 
 void render(float w, float h)
 {
-
+    static int ttt = 0;
     // Clear the colorbuffer and depth-buffer
     glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
     glViewport(0, 0, w, h);
@@ -132,7 +136,7 @@ void render(float w, float h)
 
     // Rotate and translate the model view matrix
     matModelView[ 0] = 1.0;
-    matModelView[ 2] = 0.0f;
+    matModelView[ 2] = sinf((ttt++)*0.3);
     matModelView[ 5] = 1.0f;
     matModelView[ 8] = 0.0f;
     matModelView[10] = 0.0f;
@@ -179,11 +183,12 @@ EGLDisplay gbm_init(const char* devicePath) {
     
     return  eglGetDisplay(gbmDevice);
 }
+
+#define PRINT_ERR(_str) { int _ret = glGetError();if ((_ret)!=GL_NO_ERROR) {printf(_str " ret: 0x%x\n", _ret);} }
+
 void fbo_test() {
     
-
-    int width = 800;
-    int height = 600;
+    uint32_t ret;
 
     // 创建并绑定帧缓冲对象
     glGenFramebuffers(1, &framebuffer);
@@ -194,17 +199,21 @@ void fbo_test() {
     glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer);
 
     // 分配存储空间
-    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA, fbo_width, fbo_height);
+    // PRINT_ERR("glRenderbufferStorage");
 
     // 将渲染缓冲对象附着到帧缓冲的深度和模板附着点
-    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, renderbuffer);
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, renderbuffer);
+    // PRINT_ERR("glFramebufferRenderbuffer");
+
 
     // 创建并绑定纹理对象用于颜色附着点
     glGenTextures(1, &texId);
     glBindTexture(GL_TEXTURE_2D, texId);
 
     // 分配存储空间
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, fbo_width, fbo_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+    // PRINT_ERR("glTexImage2D");
 
     // 设置纹理参数
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
@@ -215,6 +224,7 @@ void fbo_test() {
 
     // 将纹理对象附着到帧缓冲的颜色附着点
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texId, 0);
+    // PRINT_ERR("glFramebufferTexture2D");
 
     // 检查 FBO 完整性
     GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
@@ -265,7 +275,7 @@ int init(void)
 	}
 
 
-    int configIndex = matchConfigToVisual(egldisplay, GBM_FORMAT_XRGB8888, configs, numConfigs);
+    int configIndex = matchConfigToVisual(egldisplay, GBM_FORMAT_ARGB8888, configs, numConfigs);
 	if (configIndex < 0)
 	{
 		fprintf(stderr, "Failed to find matching EGL config! Error: 0x%x\n", eglGetError());
@@ -475,24 +485,18 @@ void writeToFile(const char* filename, unsigned char* data, long dataLen) {
     }
 }
 
+#define DURATION(_t1, _t2) (((_t1).tv_usec - (_t2).tv_usec))
+
 int main (void)
 {
-    EGLint width = 800;
-    EGLint height = 600;
-
     // init_signal();
     init();
-    
-    // eglQuerySurface(egldisplay, eglsurface, EGL_WIDTH, &width);
-    // eglQuerySurface(egldisplay, eglsurface, EGL_HEIGHT, &height);
 
-    printf("w=%d h=%d\n",width,height);
-
-    // thrd_t thr;
-    // thrd_create(&thr, event_handle, NULL);
+    printf("w=%d h=%d\n", fbo_width, fbo_height);
     
-    unsigned char* buffer = (unsigned char*)malloc(width * height * 4);
+    unsigned char* buffer = (unsigned char*)malloc(fbo_width * fbo_height * 4);
     fbo_test();
+    struct timeval start, end;
     while (1) {
 
         glBindTexture(GL_TEXTURE_2D, texId);
@@ -500,14 +504,19 @@ int main (void)
         glBindTexture(GL_TEXTURE_2D, 0);
 
         // glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
-        render(width,height);
+        gettimeofday(&start, NULL);
+        render(fbo_width, fbo_height);
+        gettimeofday(&end, NULL);
+        printf("render time: %ldus, %.1lf fps\n", DURATION(end, start), (1000000.0/(DURATION(end, start))));
+        // printf("render time: %ldms, %.1f fps\n", (end - start), (1000.0/(end - start)));
+
         // glBindFramebuffer(GL_FRAMEBUFFER, 0);
         printf("glReadPixels start \n");
         glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffer);
-        glReadPixels( 0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer );
+        glReadPixels( 0, 0, fbo_width, fbo_height, GL_RGBA, GL_UNSIGNED_BYTE, buffer );
         glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
         printf("glReadPixels end \n");
-        writeToFile("image.rgba", buffer, width * height * 4);
+        writeToFile("image.rgba", buffer, fbo_width * fbo_height * 4);
         // eglSwapBuffers(egldisplay, eglsurface);
         sleep(1);
     }