Android OpenGL ES – Part 8: Ambient Lighting

1. Add a directional light

1.1. Modify the fragment shader

• Open the main.cpp file.
• Modify the fragment shader source code as follows:

static const GLchar fragmentShaderSource[] =
   "#version 310 es\n"
   "precision mediump float;\n"
   "in vec4 vColor;\n"
   "in vec2 vTexCoords;\n"
   "out vec4 color;\n"
   "struct DirectionalLight\n"
   "{\n"
   "vec3 color;\n"
   "float intensity;\n"
   "};\n"
   "uniform sampler2D textureSampler;\n"
   "uniform DirectionalLight directionalLight;\n"
   "void main()\n"
   "{\n"
   "color = texture(textureSampler, vTexCoords);\n"
   "}\n";

1.2. Set the uniform variables

• Declare the following global variables:

/* code */

GLint uniformModel, uniformProjection, uniformView;
GLint uniformLightColor, uniformLightIntensity;
glm::mat4 projectionMatrix;

/* code */

• Modify the createProgram function as follows:

/* code */

uniformView = glGetUniformLocation(program, "view");

uniformLightColor = glGetUniformLocation(program, "directionalLight.color");
uniformLightIntensity = glGetUniformLocation(program, "directionalLight.intensity");

return;

/* code */

• Modify the Java_dev_anastasioscho_glestriangle_NativeLibrary_nOnDrawFrame function as follows:

/* code */

glUseProgram(program);

glUniform3f(uniformLightColor, 1.0f, 1.0f, 1.0f);
glUniform1f(uniformLightIntensity, 1.0f);

currentAngle += angleStep;

/* code */

2. Apply ambient lighting

• Modify the fragment shader source code as follows:

static const GLchar fragmentShaderSource[] =
   "#version 310 es\n"
   "precision mediump float;\n"
   "in vec4 vColor;\n"
   "in vec2 vTexCoords;\n"
   "out vec4 color;\n"
   "struct DirectionalLight\n"
   "{\n"
   "vec3 color;\n"
   "float intensity;\n"
   "};\n"
   "uniform sampler2D textureSampler;\n"
   "uniform DirectionalLight directionalLight;\n"
   "void main()\n"
   "{\n"
   "vec4 ambientColor = vec4(directionalLight.color, 1.0f) * directionalLight.intensity;\n"
   "color = texture(textureSampler, vTexCoords) * ambientColor;\n"
   "}\n";