generate random colored squares

src/PlotWindow.cpp

@@ -4,13 +4,15 @@
 #include <string>
 #include <fstream>
 
+#define frand() ((float)rand() / (float)RAND_MAX)
+
 PlotWindow::PlotWindow(int w, int h, int id, std::string title) :
 	window(nullptr), id(id), 
 	vertices{
-		-0.5f,  0.5f, 0.0f,
-		 0.5f,  0.5f, 0.0f,
-		 0.5f, -0.5f, 0.0f,
-		-0.5f, -0.5f, 0.0f
+		-0.5f,  0.5f, 0.0f, frand(), frand(), frand(),
+		 0.5f,  0.5f, 0.0f, frand(), frand(), frand(),
+		 0.5f, -0.5f, 0.0f, frand(), frand(), frand(),
+		-0.5f, -0.5f, 0.0f, frand(), frand(), frand()
 	}, 
 	indices{
 		0, 1, 3,
@@ -111,8 +113,10 @@ PlotWindow::PlotWindow(int w, int h, int id, std::string title) :
 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
 	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
 
-	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, (3 + 3) * sizeof(float), (void*)0);
+	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, (3 + 3) * sizeof(float), (void*)(3 * sizeof(float)));
 	glEnableVertexAttribArray(0);
+	glEnableVertexAttribArray(1);
 
 	glBindBuffer(GL_ARRAY_BUFFER, 0);
 	glBindVertexArray(0);

src/PlotWindow.hpp

@@ -34,6 +34,6 @@ private:
 	ShaderProgram shader;
 	BufferObject VAO, VBO, EBO;
 
-	float			vertices[4 * 3];
+	float			vertices[4 * 3 * 4];
 	unsigned int	indices[2 * 3];
 };

src/main.cpp

@@ -9,6 +9,8 @@
 
 int main(int argc, char** argv)
 {
+	srand(time(0));
+
 	int result = glfwInit();
 	if (result != GL_TRUE)
 	{

src/shader/basic.frag

@@ -1,8 +1,9 @@
 #version 460 core
 
-out vec4 oColor;
+in vec4 vertexColor;
+out vec4 fragColor;
 
 void main()
 {
-	oColor = vec4(0.6f, 0.2f, 0.9f, 1.0f);
+	fragColor = vertexColor;
 }

src/shader/basic.vert

@@ -1,8 +1,12 @@
 #version 460 core
 
 layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec3 aCol;
+
+out vec4 vertexColor;
 
 void main()
 {
-	gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
+	vertexColor = vec4(aCol, 1.0f);
+	gl_Position = vec4(aPos, 1.0f);
 }