public static void DrawLine(WebGLRenderingContext gl, WebGLProgram program, RGBAColour colour,
int x0, int y0, int x1, int y1)
{
gl.UseProgram(program);
var positionCoords = new float[]
{
x0, y0, x1, y1
};
/* Add the components of the colour twice (one for each vertex). */
var colours = new float[]
{
colour.R, colour.G, colour.B, colour.A,
colour.R, colour.G, colour.B, colour.A
};
var matrixLocation = gl.GetUniformLocation(program, "u_matrix");
/* Load the colour into a buffer and bind to shader attribute. */
var colourBuffer = gl.CreateBuffer();
var colourLocation = gl.GetAttribLocation(program, "a_color");
gl.BindBuffer(gl.ARRAY_BUFFER, colourBuffer);
gl.BufferData(gl.ARRAY_BUFFER, new Float32Array(colours), gl.STATIC_DRAW);
gl.VertexAttribPointer(colourLocation, 4, gl.FLOAT, false, 0, 0);
gl.EnableVertexAttribArray(colourLocation);
/* Load the line endpoints into a buffer and bind to shader attribute. */
var vertexBuffer = gl.CreateBuffer();
var positionLocation = gl.GetAttribLocation(program, "a_position");
gl.BindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
gl.BufferData(gl.ARRAY_BUFFER, new Float32Array(positionCoords), gl.STATIC_DRAW);
gl.VertexAttribPointer(positionLocation, 2, gl.FLOAT, false, 0, 0);
gl.EnableVertexAttribArray(positionLocation);
/* Set up projection matrix and translate to screen origin. */
var matrix = CameraHelpers.Orthographic(0, gl.Canvas.Width, gl.Canvas.Height, 0, -1, 1);
gl.UniformMatrix4fv(matrixLocation, false, matrix.ToArray());
matrix = matrix.Translate(x0 / (float)gl.Canvas.Width * 2, -y0 / (float)gl.Canvas.Height * 2, 0);
gl.DrawArrays(gl.LINES, 0, 2);
gl.BindBuffer(gl.ARRAY_BUFFER, null);
}
public static void DrawImage(WebGLRenderingContext gl, TextureInfo textureInfo, WebGLProgram program,
int xSrc, int ySrc, int srcWidth, int srcHeight,
int xDest, int yDest, int destWidth, int destHeight)
{
gl.UseProgram(program);
var positionLocation = gl.GetAttribLocation(program, "a_position");
var texCoordLocation = gl.GetAttribLocation(program, "a_texcoord");
var matrixLocation = gl.GetUniformLocation(program, "u_matrix");
var textureLocation = gl.GetUniformLocation(program, "u_texture");
/* Create a buffer to hold the position coordinates. */
var positionBuffer = gl.CreateBuffer();
var positionCoords = new float[]
{
0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1
};
gl.BindBuffer(gl.ARRAY_BUFFER, positionBuffer);
gl.BufferData(gl.ARRAY_BUFFER, new Float32Array(positionCoords), gl.STATIC_DRAW);
/* Create a buffer to hold the texture coordinates. */
var sx = xSrc / (float)textureInfo.Width.Value;
var sy = ySrc / (float)textureInfo.Height.Value;
var sw = srcWidth / (float)textureInfo.Width.Value;
var sh = srcHeight / (float)textureInfo.Height.Value;
var texBuffer = gl.CreateBuffer();
var texCoords = new float[]
{
0 + sx, 0 + sy,
0 + sx, sh + sy,
sw + sx, 0 + sy,
sw + sx, 0 + sy,
0 + sx, sh + sy,
sw + sx, sh + sy
};
gl.BindBuffer(gl.ARRAY_BUFFER, texBuffer);
gl.BufferData(gl.ARRAY_BUFFER, new Float32Array(texCoords), gl.STATIC_DRAW);
gl.BindTexture(gl.TEXTURE_2D, textureInfo.Texture);
gl.BindBuffer(gl.ARRAY_BUFFER, positionBuffer);
gl.EnableVertexAttribArray(positionLocation);
gl.VertexAttribPointer(positionLocation, 2, gl.FLOAT, false, 0, 0);
gl.BindBuffer(gl.ARRAY_BUFFER, texBuffer);
gl.EnableVertexAttribArray(texCoordLocation);
gl.VertexAttribPointer(texCoordLocation, 2, gl.FLOAT, false, 0, 0);
/* Create an standard orthographic projection to transform our coordinates by and bind to our shader uniform. */
var matrix = CameraHelpers.Orthographic(0, gl.Canvas.Width, gl.Canvas.Height, 0, -1, 1);
matrix = matrix.Translate(xDest / (float)gl.Canvas.Width * 2, -yDest / (float)gl.Canvas.Height * 2, 0);
matrix = matrix.Scale(destWidth, destHeight, 1);
gl.UniformMatrix4fv(matrixLocation, false, matrix.ToArray());
gl.Uniform1i(textureLocation, 0);
/* 6 points per image rendered as two triangles. */
gl.DrawArrays(gl.TRIANGLES, 0, 6);
gl.BindBuffer(gl.ARRAY_BUFFER, null);
}
