Unwanted transparency in Phong Shader - GLSL

Question

I am trying to create a basic Phong lighting shader to learn about lighting in shaders. In addition, I use openframeworks. I created 3 cubes around which the camera revolved. The lighting seems to work (sorta), but the cubes have undesirable transparency, which you can see here:

Here is my code based on this tutorial

testApp.h

#pragma once #include "ofMain.h" class testApp : public ofBaseApp{ public: ofCamera camera; ofLight pointLight; float camAngle; float camX; float camY; float camZ; ofShader lightShader; ofBoxPrimitive box1; ofBoxPrimitive box2; ofBoxPrimitive box3; void setup(); void update(); void draw(); }; 

testApp.cpp

 #include "testApp.h" //-------------------------------------------------------------- void testApp::setup() { glEnable(GL_DEPTH_TEST); glEnable(GL_LIGHTING); ofBackground(100, 100, 100); ofSetFrameRate(30); camera.setNearClip(0.1); camera.setFarClip(1200); camAngle = 0; camX = 200; camY = 150; camZ = 200; pointLight.setPointLight(); lightShader.load("shaders/lightShader"); //boxes setup here, not necessary to show } //-------------------------------------------------------------- void testApp::update() { camAngle += 0.01f; if (camAngle >= 360) { camAngle = 0; } camX = 300 * sin(camAngle); camZ = 300 * cos(camAngle); camera.lookAt(ofVec3f(0, 0, 0)); camera.setPosition(ofVec3f(camX, camY, camZ)); pointLight.setPosition(-50, -20, 200); } //-------------------------------------------------------------- void testApp::draw() { lightShader.begin(); camera.begin(); pointLight.enable(); pointLight.draw(); ofVec3f lightLocation = pointLight.getPosition(); lightShader.setUniform3f("lightLocation", lightLocation.x, lightLocation.y, lightLocation.z); box1.draw(); ofPushMatrix(); ofTranslate(60, 50); ofRotate(45, 1.0, 0.0, 0.0); box2.draw(); ofPopMatrix(); ofPushMatrix(); ofTranslate(-70,70); ofRotate(110, 1.0, 0.0, 0.6); box3.draw(); ofPopMatrix(); pointLight.disable(); camera.end(); lightShader.end(); } 

lightShader.vert

 // vertex shader #version 150 //these are passed in by openframeworks uniform mat4 modelViewProjectionMatrix; in vec4 position; in vec4 color; in vec3 normal; in vec2 texcoord; out vec4 vertPosition; out vec4 vertColor; out vec3 vertNormal; out vec2 texCoordVar; void main() { texCoordVar = texcoord; vertPosition = position; vertColor = color; vertNormal = normal; gl_Position = modelViewProjectionMatrix * position; } 

lightShader.frag

 // fragment shader #version 150 uniform mat4 modelViewMatrix; uniform mat4 modelViewProjectionMatrix; uniform vec3 lightLocation; uniform vec3 lightIntensity; in vec2 texCoordVar; in vec3 vertNormal; in vec4 vertPosition; in vec4 vertColor; out vec4 outputColor; void main() { //calculate normal in world coordinates mat3 normalMatrix = transpose(inverse(mat3(modelViewMatrix))); vec3 vertexNormal = normalize(normalMatrix * vertNormal); //calculate the location of this pixel in world coordinates vec3 fragPosition = vec3(modelViewMatrix * vertPosition); //calculate the vector from this pixels surface to the light source vec3 surfaceToLight = normalize(lightLocation - fragPosition); //calculate the cosine of the angle of incidence (brightness) float brightness = max(0.0, dot(vertexNormal, surfaceToLight)); //calculate final color of the pixel outputColor = brightness * vec4(vertColor.rgb, 1.0); } 

In some experiments, I found that if I changed the last line of the fragment shader to this:

 outputColor = brightness * (vec4(vertColor.rgb, 1.0) * modelViewProjectionMatrix); 

I get this:

The colors are wrong and the lighting becomes very black, but the objects are opaque, as it should be. So maybe I should somehow use modelViewProjectionMatrix? I don’t know how to do it.

Answer 1

You increase the brightness on the alpha channel:

 outputColor = brightness * vec4(vertColor.rgb, 1.0); 

You can do something like this:

 outputColor = brightness * vec4(vertColor.rgb, 1.0); 

and then:

 outputColor.a = 1.0; 

No, you do not need to use modelViewProjectionMatrix as follows:

 outputColor = brightness*(vec4(vertColor.rgb, 1.0) * modelViewProjectionMatrix); 

You just need modelViewProjectionMatrix to get the screen coordinate for the top