From baef478bbacea2204b2e8528c7b5da3fe8915407 Mon Sep 17 00:00:00 2001
From: mmcwilliams <hi@mmcwilliams.com>
Date: Mon, 1 Apr 2024 17:45:50 -0400
Subject: [PATCH] Texture loads but is drawn at right angle

---
 main.cpp | 80 +++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 59 insertions(+), 21 deletions(-)

diff --git a/main.cpp b/main.cpp
index 6c5421b..4f50f1e 100644
--- a/main.cpp
+++ b/main.cpp
@@ -26,49 +26,87 @@ GLint screenWidth = 0;
 GLint screenHeight = 0;
 time_stamp ts;
 
-void getScreenDimensions () {
+void loadTexture (GLuint& imageTexture1)
+{
+  string image_path = samples::findFile("chart.png");
+  Mat image = imread(image_path, IMREAD_COLOR);
+  if (image.empty()) {
+      cout << "image empty" << endl;
+  } else {
+      cout << "loaded " << image_path << endl;
+      //flip(image, image, 1);
+#if (CV_VERSION_MAJOR >= 4)
+      cvtColor(image, image, cv::COLOR_BGR2RGB);
+#else
+      cvtColor(image, image, CV_BGR2RGB);
+#endif
+      //glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
+      glGenTextures(1, &imageTexture1);
+      glBindTexture(GL_TEXTURE_2D, imageTexture1);
+
+      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        // Set texture clamping method
+      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
+      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
+
+      glTexImage2D(GL_TEXTURE_2D,            // Type of texture
+                        0,                   // Pyramid level (for mip-mapping) - 0 is the top level
+                        GL_RGB,              // Internal colour format to convert to
+                        image.cols,          // Image width  i.e. 640 for Kinect in standard mode
+                        image.rows,          // Image height i.e. 480 for Kinect in standard mode
+                        0,                   // Border width in pixels (can either be 1 or 0)
+                        GL_RGB,              // Input image format (i.e. GL_RGB, GL_RGBA, GL_BGR etc.)
+                        GL_UNSIGNED_BYTE,    // Image data type
+                        image.ptr());        // The actual image data itself
+    }
+}
+
+void getScreenDimensions ()
+{
   if (screenWidth == 0 && screenHeight == 0) {
     GLint dims[4] = {0};
     glGetIntegerv(GL_VIEWPORT, dims);
     screenWidth = dims[2];
     screenHeight = dims[3];
     cout << screenWidth << "," << screenHeight << endl;
+    loadTexture(imageTexture);
   }
 }
  
-void displayMe(void)
+void display(void)
 {
   getScreenDimensions();
-
-  string image_path = samples::findFile("chart.png");
-  Mat image = imread(image_path, IMREAD_COLOR);
-  #if (CV_VERSION_MAJOR >= 4)
-    cvtColor(image, image, cv::COLOR_BGR2RGB);
-  #else
-    cvtColor(image, image, CV_BGR2RGB);
-  #endif
+  ts = time_point_cast<microseconds>(system_clock::now());
   
-  // Set every pixel in the frame buffer to the current clear color.
   glClear(GL_COLOR_BUFFER_BIT);
-  glBegin(GL_POLYGON);
-    glColor3f(1, 0, 0); glVertex3f(-1.0, -1.0, 0.5);
-    glColor3f(0, 1, 0); glVertex3f(1.0, -1.0, 0);
-    glColor3f(0, 0, 1); glVertex3f(1.0, 1.0, 0);
-    glColor3f(0, 0, 0); glVertex3f(-1.0, 1.0, 0);
-  glEnd();
+  glEnable(GL_TEXTURE_2D);
+  //glViewport(0, 0, screenWidth, screenHeight);
+  glMatrixMode(GL_PROJECTION);
+  glLoadIdentity();
+  
+  glBindTexture(GL_TEXTURE_2D, imageTexture);
 
-  // Flush drawing command buffer to make drawing happen as soon as possible.
-  glFlush();
+  glBegin(GL_QUADS);  // front face
+  glTexCoord2f(0.0f, 0.0f); glVertex3f(1.0f, -1.0f, 0.0f);  //bottom right
+  glTexCoord2f(1.0f, 0.0f); glVertex3f(1.0f, 1.0f, 0.0f);   //top right
+  glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f);  //top left
+  glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, -1.0f, 0.0f); //bottom left
+  glEnd();
+  glDisable(GL_TEXTURE_2D);
+  glutSwapBuffers();
+
+  //glFlush();
 }
  
 int main(int argc, char** argv)
 {
-    ts = time_point_cast<microseconds>(system_clock::now());
     glutInit(&argc, argv);
     glutInitDisplayMode(GLUT_SINGLE);
     glutCreateWindow("opengl_opencv_example");
     glutFullScreen();
-    glutDisplayFunc(displayMe);
+    glutDisplayFunc(display);
     glutMainLoop();
     return 0;
 }
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