From 6f68cb9a60c037251927d4fe49cedf575fab4c72 Mon Sep 17 00:00:00 2001
From: Even Oscar Andersen <even.oscar.andersen@qt.io>
Date: Mon, 18 Mar 2024 14:12:26 +0100
Subject: wasm: Fix openglwindow example

Use QOpenGLBuffer to satisfy WebGL

Change-Id: Id40a85feb329a85844637c5f5a7a8ae534969086
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
---
 examples/opengl/openglwindow/main.cpp | 81 ++++++++++++++++-------------------
 1 file changed, 38 insertions(+), 43 deletions(-)

(limited to 'examples/opengl/openglwindow')

diff --git a/examples/opengl/openglwindow/main.cpp b/examples/opengl/openglwindow/main.cpp
index 6813dc9efd..89933fa379 100644
--- a/examples/opengl/openglwindow/main.cpp
+++ b/examples/opengl/openglwindow/main.cpp
@@ -6,10 +6,10 @@
 #include <QGuiApplication>
 #include <QMatrix4x4>
 #include <QOpenGLShaderProgram>
+#include <QOpenGLBuffer>
 #include <QScreen>
 #include <QtMath>
 
-
 //! [1]
 class TriangleWindow : public OpenGLWindow
 {
@@ -20,10 +20,8 @@ public:
     void render() override;
 
 private:
-    GLint m_posAttr = 0;
-    GLint m_colAttr = 0;
     GLint m_matrixUniform = 0;
-
+    QOpenGLBuffer m_vbo;
     QOpenGLShaderProgram *m_program = nullptr;
     int m_frame = 0;
 };
@@ -48,36 +46,48 @@ int main(int argc, char **argv)
 }
 //! [2]
 
-
 //! [3]
-static const char *vertexShaderSource =
-    "attribute highp vec4 posAttr;\n"
-    "attribute lowp vec4 colAttr;\n"
-    "varying lowp vec4 col;\n"
-    "uniform highp mat4 matrix;\n"
-    "void main() {\n"
-    "   col = colAttr;\n"
-    "   gl_Position = matrix * posAttr;\n"
-    "}\n";
-
-static const char *fragmentShaderSource =
-    "varying lowp vec4 col;\n"
-    "void main() {\n"
-    "   gl_FragColor = col;\n"
-    "}\n";
+static const char *vertexShaderSource = "attribute highp vec4 posAttr;\n"
+                                        "attribute lowp vec4 colAttr;\n"
+                                        "varying lowp vec4 col;\n"
+                                        "uniform highp mat4 matrix;\n"
+                                        "void main() {\n"
+                                        "   col = colAttr;\n"
+                                        "   gl_Position = matrix * posAttr;\n"
+                                        "}\n";
+
+static const char *fragmentShaderSource = "varying lowp vec4 col;\n"
+                                          "void main() {\n"
+                                          "   gl_FragColor = col;\n"
+                                          "}\n";
 //! [3]
 
 //! [4]
 void TriangleWindow::initialize()
 {
+    static const GLfloat vertices_colors[] = { +0.0f, +0.707f, 1.0f, 0.0f, 0.0f,
+                                               -0.5f, -0.500f, 0.0f, 1.0f, 0.0f,
+                                               +0.5f, -0.500f, 0.0f, 0.0f, 1.0f };
+
+    m_vbo.create();
+    m_vbo.bind();
+    m_vbo.allocate(vertices_colors, sizeof(vertices_colors));
+
+    glEnableVertexAttribArray(0);
+    glEnableVertexAttribArray(1);
+
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), nullptr);
+    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat),
+                          reinterpret_cast<void *>(2 * sizeof(GLfloat)));
+
     m_program = new QOpenGLShaderProgram(this);
     m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, vertexShaderSource);
     m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShaderSource);
+    m_program->bindAttributeLocation("posAttr", 0);
+    m_program->bindAttributeLocation("colAttr", 1);
     m_program->link();
-    m_posAttr = m_program->attributeLocation("posAttr");
-    Q_ASSERT(m_posAttr != -1);
-    m_colAttr = m_program->attributeLocation("colAttr");
-    Q_ASSERT(m_colAttr != -1);
+    m_program->bind();
+
     m_matrixUniform = m_program->uniformLocation("matrix");
     Q_ASSERT(m_matrixUniform != -1);
 }
@@ -100,28 +110,13 @@ void TriangleWindow::render()
 
     m_program->setUniformValue(m_matrixUniform, matrix);
 
-    static const GLfloat vertices[] = {
-         0.0f,  0.707f,
-        -0.5f, -0.5f,
-         0.5f, -0.5f
-    };
-
-    static const GLfloat colors[] = {
-        1.0f, 0.0f, 0.0f,
-        0.0f, 1.0f, 0.0f,
-        0.0f, 0.0f, 1.0f
-    };
-
-    glVertexAttribPointer(m_posAttr, 2, GL_FLOAT, GL_FALSE, 0, vertices);
-    glVertexAttribPointer(m_colAttr, 3, GL_FLOAT, GL_FALSE, 0, colors);
-
-    glEnableVertexAttribArray(m_posAttr);
-    glEnableVertexAttribArray(m_colAttr);
+    glEnableVertexAttribArray(0);
+    glEnableVertexAttribArray(1);
 
     glDrawArrays(GL_TRIANGLES, 0, 3);
 
-    glDisableVertexAttribArray(m_colAttr);
-    glDisableVertexAttribArray(m_posAttr);
+    glDisableVertexAttribArray(0);
+    glDisableVertexAttribArray(1);
 
     m_program->release();
 
-- 
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