fft_heightmap.glsl.vert.h

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#include "shaders_common.h"

static const char *fft_vertex_program_heightmap = GLSL_300(
 layout(location = 0) in vec2 aVertex;
 uniform sampler2D sHeight;
 uniform mat4 uMVP;
 uniform ivec2 uOffset;
 uniform vec4 uHeightmapParams;
 uniform float uAngleScale;
 out vec3 vWorldPos;
 out vec3 vHeight;

 void main() {
 vec2 tex_coord = vec2(aVertex.x + float(uOffset.x) + 0.5, -aVertex.y + float(uOffset.y) + 0.5) / vec2(textureSize(sHeight, 0));

 vec3 world_pos = vec3(aVertex.x, 0.0, aVertex.y);
 world_pos.xz += uHeightmapParams.xy;

 float angle = world_pos.x * uAngleScale;
 world_pos.xz *= uHeightmapParams.zw;

 float lod = log2(world_pos.z + 1.0) - 6.0;
 vec4 heights = textureLod(sHeight, tex_coord, lod);

 float cangle = cos(angle);
 float sangle = sin(angle);

 int c = int(-sign(world_pos.x) + 1.0);
 float height = mix(heights[c], heights[1], abs(angle) / 3.141592653);
 height = height * 80.0 - 40.0;

 vec3 up = vec3(-sangle, cangle, 0.0);

 float base_y = 80.0 - 80.0 * cangle;
 float base_x = 80.0 * sangle;
 world_pos.xy = vec2(base_x, base_y);
 world_pos += up * height;

 vWorldPos = world_pos;
 vHeight = vec3(height, heights.yw * 80.0 - 40.0);
 gl_Position = uMVP * vec4(world_pos, 1.0);
 }
);