Rendering using shaders only

ShadowDragon · December 24, 2022, 6:40am

Hi, hope you won’t mind helping me.

I am trying to implement a procedural skybox in my openGL app which renders meshes with textures just fine and gives no GL_ERRORS, all shaders complile, however the skyBox will not render and I can’t track down the bug.

The shaders I borrowed do not ask for any input, a quad is defines in the vertex shader and passed on through the pipeline.

github.com

shff/opengl_sky/blob/master/main.c

#define GLFW_INCLUDE_GLCOREARB
#include <GLFW/glfw3.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

#define GL(line) do { line; assert(glGetError() == GL_NO_ERROR); } while(0)
#define GLSL(str) (const char*)"#version 330\n" #str

// Regular Shaders

const char* vertShader = GLSL(
  layout(location = 0) in vec3 position;
  layout(location = 1) in vec2 vUV;
  uniform mat4 P;
  uniform mat4 V;
  out vec2 fUV;

  void main()

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So in my code I set up a VAO and VBO and bound NULL data with a size of 0.

Then glDrawArrays with a count of 4

Am I on the right track and hunting for a typo? Or is this totally wrong?

Here is my code - check out SkyBoxRenderer.h, OpenGLShader.h, SkyBox.h

aidandavey/ConsoleApplication8 (github.com)

ShadowDragon · December 31, 2022, 9:42am

UPDATE: Can confirm this now renders something - I set the frag colour to red and now get a red triangle (which is not projected where I expected it to be).

So I think I have two issues, one in getting the points into clip space correctly, and the second in determining the colour output.

But the GL code I had seems to work.