Two shaders on one object - c++

Question

I have problem with multiply shaders on my one object.
That's my render code:
#include "MeshRenderer.h"
ForwardAmbient* shader1;
ForwardDirectional* shader2;
MeshRenderer::MeshRenderer(Obj& obj) :
meshObject(obj)
{
shader1 = new ForwardAmbient(vec3(1, 1, 1));
shader2 = new ForwardDirectional(vec3(1, 0, 0), vec3(1, 1, 1));
}
MeshRenderer::~MeshRenderer()
{
}
void MeshRenderer::Render(RenderingCore* rc)
{
//for (Shader* shader : meshObject.shaders)
//{
//}
shader1->Bind();
shader1->UpdateShader(rc, transform, meshObject.material);
meshObject.material->GetTexture()->Bind(0);
meshObject.mesh->Render();
shader2->Bind();
shader2->UpdateShader(rc, transform, meshObject.material);
meshObject.material->GetTexture()->Bind(0);
meshObject.mesh->Render();
/*
meshObject.shader->Bind();
meshObject.shader->UpdateShader(rc, transform, meshObject.material);
meshObject.material->GetTexture()->Bind(0);
meshObject.mesh->Render();
*/
}
ambient light.vs:
#version 120
attribute vec3 position;
attribute vec2 texCoord;
attribute vec3 normal;
varying vec2 texCoord0;
uniform mat4 transform;
uniform mat4 projection;
void main()
{
gl_Position = (projection * transform) * vec4(position, 1);
texCoord0 = texCoord;
}
ambient light.fs:
#version 120
varying vec2 texCoord0;
uniform vec3 ambientLight;
uniform float alpha;
uniform sampler2D sampler;
void main()
{
gl_FragColor = texture2D(sampler, texCoord0.xy) * vec4(ambientLight, alpha);
}
directional light.vs
#version 120
attribute vec3 position;
attribute vec2 texCoord;
attribute vec3 normal;
varying vec2 texCoord0;
varying vec3 normal0;
varying vec3 worldPos0;
uniform mat4 transform;
uniform mat4 projection;
void main()
{
gl_Position = (projection * transform) * vec4(position, 1);
texCoord0 = texCoord;
normal0 = (transform * vec4(normal, 0)).xyz;
worldPos0 = (transform * vec4(position, 1)).xyz;
}
directional light.fs
#version 120
varying vec2 texCoord0;
varying vec3 normal0;
varying vec3 worldPos0;
uniform vec3 color;
uniform float alpha;
uniform vec3 direction;
uniform float specularIntensity;
uniform float specularPower;
uniform vec3 eyePosition;
uniform sampler2D sampler;
vec4 calcLight(vec3 color, float alpha, vec3 direction, vec3 normal)
{
float diffuseFactor = dot(normal, -direction);
vec4 diffuseColor = vec4(0,0,0,0);
vec4 specularColor = vec4(0,0,0,0);
if(diffuseFactor > 0)
{
diffuseColor = vec4(color, 1.0) * diffuseFactor;
vec3 directionToEye = normalize(eyePosition - worldPos0);
vec3 reflectDirection = normalize(reflect(direction, normal));
float specularFactor = dot(directionToEye, reflectDirection);
specularFactor = pow(specularFactor, specularPower);
if(specularFactor > 0)
{
specularColor = vec4(color, 1.0) * specularIntensity * specularFactor;
}
}
return diffuseColor + specularColor;
}
vec4 calcDirectionalLight(vec3 color, float alpha, vec3 direction, vec3 normal)
{
return calcLight(color, alpha, -direction, normal);
}
void main()
{
gl_FragColor = texture2D(sampler, texCoord0.xy) * calcDirectionalLight(color, 1, direction, normalize(normal0));
}
Here is the result:
http://imgur.com/Bawny2P
Only ambient light is render, directional light no

Answer 1

Your problem is this:
shader1->Bind();
shader1->UpdateShader(rc, transform, meshObject.material);
meshObject.material->GetTexture()->Bind(0);
meshObject.mesh->Render();
shader2->Bind();
shader2->UpdateShader(rc, transform, meshObject.material);
meshObject.material->GetTexture()->Bind(0);
meshObject.mesh->Render();
OpenGL doesn't know what "object" are. It just draws points, lines and triangles, one at a time. To sort out depth overlap the depth buffer method is used. When you use exactly the same drawing call (meshObject.mesh->Render) with all the same vertex setup and depth testing enabled then one of the two draw calls will win over the other.
Also, more importantly, drawing calls don't "stack". You simply can not combine shaders simply by drawing the same thing multiple times; it may sort of work for additive processes. But that's barking up the wrong tree: Instead of saving additional work, you're duplicating the amount of work to be done.
What you should do instead is merging the two shaders into single one and draw the geometry only once, with the merged shader.