一个物体上的两个着色器

Question

我在一个对象上使用乘法着色器时遇到问题。那是我的渲染代码：

#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();
    */
}

环境 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;
}

环境 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);
}

定向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;
}

定向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));
}

结果如下： http://imgur.com/Bawny2P 只渲染环境光，定向光没有

Answer 1

你的问题是这样的：

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 不知道 "object" 是什么。它只是一次绘制一个点、线和三角形。为了解决深度重叠，使用了深度缓冲方法。当您使用完全相同的绘图调用 (meshObject.mesh->Render) 并启用所有相同的顶点设置和深度测试时，两个绘图调用之一将胜过另一个。

此外，更重要的是，绘图调用不会 "stack"。您根本无法简单地通过多次绘制同一事物来组合着色器；它可能适用于增材工艺。但这是在树错了树：你不是在节省额外的工作，而是在重复要完成的工作量。

您应该做的是将两个着色器合并为一个着色器，并使用合并后的着色器只绘制一次几何体。

一个物体上的两个着色器

Two shaders on one object

c++

opengl

shader

rendering